Media clip management

ABSTRACT

Some embodiments provide a method for editing a composite presentation in a media-editing application. The method receives a media file to import into the media-editing application from an external device. The method creates a set of media clip data structures to represent the media file. At least one of the data structures references the media file on the external device. Before the media file is imported from the external device, the method uses the media clip data structure to edit a composite presentation with the media file. After the media file is imported from the external device, automatically modifying the data structure to refer to a copy of the media file on a local device.

CLAIM OF BENEFIT TO PRIOR APPLICATION

This application claims the benefit of U.S. Provisional Application61/443,707, entitled “Efficient Media Processing”, filed Feb. 16, 2011.This application also claims the benefit of U.S. Provisional Application61/437,517, entitled “Media-Editing Application with Video SegmentationCa abilities and Automatic Back round-Render” filed Jan. 28, 2011. Thisapplication also claims the benefit of U.S. Provisional Application61/443,702, entitled “Media-Editing Application with Anchored Timeline”,filed Feb. 16, 2011. This application also claims the benefit of U.S.Provisional Application 61/443,704 entitled “Media-Editing Applicationwith Novel Editing Tools”, filed Feb. 16, 2011. U.S. ProvisionalApplication 61/443,707 is incorporated herein by reference.

CROSS REFERENCE TO RELATED APPLICATIONS

This Application is related to the following applications: U.S. patentapplication Ser. No. 13/111,890, filed May 19, 2011; U.S. patentapplication Ser. No. 13/111,892, filed May 19, 2011; U.S. patentapplication Ser. No. 13/111,895, filed May 19, 2011; and U.S. patentapplication Ser. No. 13/111,912, filed May 19, 2011.

BACKGROUND

Digital graphic design, image editing, audio editing, and video editingapplications (hereafter collectively referred to as media contentediting applications or media editing applications) provide graphicaldesigners, media artists, and other users with the necessary tools tocreate a variety of media content. Examples of such applications includeFinal Cut Pro® and iMovie®, both sold by Apple, Inc. These applicationsgive users the ability to edit, combine, transition, overlay, and piecetogether different media content in a variety of manners to create aresulting media project. The resulting media project specifies aparticular sequenced composition of any number of text, audio, image,and/or video content elements that is used to create a mediapresentation.

Various media editing applications facilitate such composition throughelectronic means. Specifically, a computer or other electronic devicewith a processor and computer readable storage medium executes the mediaediting application. In so doing, the computer generates a graphicalinterface whereby designers digitally manipulate graphicalrepresentations of the media content to produce a desired result.

In many cases, the import process for importing video into theapplication may be an extremely time-intensive process. Variousoperations will be performed on the video, and each of these operationsrequires separate processing. For large amounts of media, this can takesignificant amounts of time.

BRIEF SUMMARY

Some embodiments of the invention provide a media-editing applicationthat performs one or more destination operations on a media file (e.g.,video files, audio files, etc.) in parallel upon import of the mediafile. Rather than performing fully separate processing for eachoperation, the media-editing application performs certain imagepreparation operations (e.g., disk read, decode, format conversions)only once whenever possible, then sends the same image data to thedifferent destination operations.

In some embodiments, the media-editing application is an applicationthat enables a user to create a composite media presentation from a setof media files. Through a graphical user interface (GUI) of theapplication, the user specifies the manner in which the media files arecomposited to create the composite presentation. In addition, throughthis GUI, the user can command the application to import one or moremedia files (e.g., from a camera, from an external drive, from aninternal drive, etc.). Upon instructions from the user (i.e., throughthe media-editing application GUI) or as an automatic response to thedetection of the media files in an external storage, the applicationcopies the media files to a particular media storage location on aparticular storage device. Some embodiments create a particular folderwithin the folder structure of the storage device for a set of importedmedia files (i.e., the media files imported at a particular time) andstore a copy of the imported files in this particular folder at time ofimport.

In some embodiments, upon import of a media file, the images of themedia file are automatically sent to one or more destinations forprocessing. At time of import, these destinations may include encodingoperations and analysis operations. Some embodiments store one or moreversions of an imported media file in encoded formats that areparticularly suitable for editing. For example, the application mightstore a high-resolution encoded version and a low-resolution encodedversion of a media file, in addition to the original copy (which mayalso be encoded in a different format).

In some embodiments, when a user indicates that he wants to import oneor more media files, the application presents the user with a set ofoptions that enable the user to select operations for the applicationperform on the imported media. These operations may include the high andlow-resolution encoding, various video analysis operations (e.g., colorbalancing, face and/or person detection, shake detection, etc.) andaudio analysis operations (e.g., identifying latent audio channels,identifying stereo pairs of channels, enhancing the audio, etc.). Thedata from these analysis operations may be stored in one or more filesin some embodiments.

With all of the destination operations being performed at once, theapplication will only need to perform the image preparation operationsrequired to retrieve an image for these destinations operations once foreach image of an imported media file. In some embodiments, a schedulingengine manages the performance of the various image preparationoperations in order to prepare the images for the destinations. Thescheduling engine of some embodiments schedules disk reads (i.e., diskI/O calls), decodes, and image processing operations. When theapplication is sending a media file to multiple destinations, the enginewill schedule only one disk read and one decode for each image in themedia file. This prevents duplicative disk reads and decodes from beingperformed. When all of the destinations require the image in the sameformat (i.e., the same size and colorspace), the scheduling engine willperform any necessary conversions to this desired format only once aswell. When different destinations need images in different formats, someembodiments will fan-out the operations as late as possible to minimizethe number of processing operations that need to be performed.

In addition to performing the various image operations (e.g., encodingand analysis) at time of import, some embodiments can perform these andother image operations post-import. Furthermore, video playback (andother real-time destinations that accompany playback) may be anadditional post-import destination, as well as background rendering(i.e., the preparation of output images for portions of a video sequencein advance).

In some embodiments, the scheduling engine schedules operationsdifferently for real-time operations (e.g., playback) than fornon-real-time operations (e.g., analysis, encoding, etc.). For real-timeoperations, the most important factor in how fast to schedule images isto keep up with the display rate for the video. For instance, for 24frames per second (fps) video, the scheduling engine attempts to ensurethat images are being sent to the playback operation fast enough for acontinuous display of the video. When a clock in the scheduling engineindicates that the images are falling behind, the scheduling engine mayopt to skip (i.e., drop) images and schedule ahead so as to keep up withreal time. This also enables the media-editing application of someembodiments to modify its playback in real-time as the user edits acomposite presentation in the timeline.

On the other hand, for destinations such as an encoder, a colorbalancer, etc., it is more important to receive every image than toreceive the images at a particular rate. Thus, the scheduling engine ofsome embodiments will send images to these destinations based on whenthe destinations finish processing previous images as opposed to anyclock that correlates to actual time.

When importing a media file, some embodiments create a media clip datastructure for the imported media that links to the media file, anytranscoded versions of the media file, and any analysis data about themedia file. This media clip is the entity that is added to a mediapresentation in some embodiments in order to include the media file (ora portion of the media file) in the composite presentation. Someembodiments store this information in an asset data structure thatspecifically references the media and analysis files, and thenadditionally create a clip data structure that references the asset. Inaddition, the asset data structure may include metadata such as auniversally unique identifier (UUID) for the media file generated by thecamera that captured the media, file format information, various videoproperties (e.g., frame rate, colorspace, pixel transform, dimensions,etc.), and various audio properties (e.g., channel count, track count,sample rate, etc.) of the media.

The references stored in the media clip (or asset) refer to the versionsof the media file stored in the application's file storage. Someembodiments, for each set of imported media files, create separatefolders for the original media and any type of transcoded media. In someembodiments, the transcoded media include both high-resolution andlow-resolution encodes of the original media file that may be created onimport or post-import.

In some embodiments, these references to the files are pointers to thelocations of the files on the storage device. In some embodiments, themedia-editing application initially sets the reference to the originalmedia such that the data structure references the media file that is tobe imported (e.g., the file on a camera) as the original media, thenmodifies this reference once the media file is copied to theapplication's file storage so that the data structure now references themedia in the file storage. In some such embodiments, the applicationdisplays the media clips for the user to edit before the file isactually copied. This enables a user to begin creating a presentationusing the media clip while the clip refers to a file stored on a camera,and then continue using the same clip once the file is copied with nointerruption to the editing workflow.

Much like the folders for different versions of media files, someembodiments create separate folders within a folder for a set ofimported files for each type of analysis file (e.g., a folder for persondetection files, a folder for color balance files, a folder for shakedetection files, etc.). In addition, some embodiments store additionalclip data in the media clip, as opposed to a separate file. As oneexample, some embodiments store shake detection as a tag about the mediafile or a specific portion of the media file.

Having data structures that refer to each of the different versions ofmedia enables the media-editing application of some embodiments toseamlessly switch between editing and playback in high- andlow-resolution. When a user requests high-resolution editing, theapplication reads images from the original media or the high-resolutiontranscoded media (enabling better image quality), whereas when a userrequests low-resolution editing the application reads images from thelow-resolution transcoded media (enabling faster processing). Someembodiments attach a pixel transform to each image that specifies atransform of the image from an image space in which many editingoperations are defined into the pixel space of the image. Attaching thepixel transforms to the images in the image processing pipeline enablesthe editing operations to be defined independent of the size and type ofimages being received, and thus makes possible the seamless transitionbetween using high- and low-resolution files for editing.

As mentioned, for each imported media file, some embodiments create bothan asset data structure that stores references to the different versionsof the imported media file and a clip data structure that refers to theasset. Some embodiments create a nested series of clip structures forthe imported file, including a first clip structure that refers to theasset and a second clip structure that contains the first clipstructure. The second clip structure may be contained within a datastructure that stores several associated clips and assets. When a useradds the media clip to a composite presentation, some embodimentsduplicate the first and second clip structures and add these structuresto a data structure for the composite presentation.

In the course of editing, projects will be unable to identify theunderlying media from time to time. An asset might be deleted, an assetmight exist but reference a file that no longer exists, etc. Someembodiments provide various mechanisms to modify the clip or projectreferences in order to restore the media in the project (e.g., finding adifferent asset in the application that refers to a copy of the samemedia file).

In addition, some embodiments allow a user to create archives of themedia on a camera in a bundle from which the files can be laterimported. If a user deletes all of the media (i.e., to save disk space),the user can restore this media from camera archives and the applicationwill be able to identify the media files (using a file identifier) andrestore its missing references.

The preceding Summary is intended to serve as a brief introduction tosome embodiments of the invention. It is not meant to be an introductionor overview of all inventive subject matter disclosed in this document.The Detailed Description that follows and the Drawings that are referredto in the Detailed Description will further describe the embodimentsdescribed in the Summary as well as other embodiments. Accordingly, tounderstand all the embodiments described by this document, a full reviewof the Summary, Detailed Description and the Drawings is needed.Moreover, the claimed subject matters are not to be limited by theillustrative details in the Summary, Detailed Description and theDrawing, but rather are to be defined by the appended claims, becausethe claimed subject matters can be embodied in other specific formswithout departing from the spirit of the subject matters.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth in the appendedclaims. However, for purposes of explanation, several embodiments of theinvention are set forth in the following figures.

FIG. 1 conceptually illustrates the software architecture of amedia-editing application of some embodiments.

FIG. 2 conceptually illustrates a media clip of some embodiments.

FIG. 3 illustrates a graphical user interface (GUI) of a media-editingapplication of some embodiments.

FIG. 4 illustrates the import process of some embodiments in fourstages.

FIG. 5 conceptually illustrates a process of some embodiments fordetermining whether or not to recommend a high-resolution transcode tothe user.

FIG. 6 illustrates an example of a situation in which the media-editingapplication would generate both a high-resolution and a low-resolutiontranscode of a media file.

FIG. 7 illustrates an example of a situation in which the media-editingapplication would generate only a low-resolution transcode of a mediafile.

FIG. 8 conceptually illustrates a process of some embodiments forimporting media with a media-editing application.

FIG. 9 illustrates the import of a media file from a device and then thedisconnection of the device while the application transcodes the mediafile.

FIG. 10 illustrates a system with examples of specific destinations towhich the decoder may send decoded images, as well as the output ofthose destinations.

FIG. 11 conceptually illustrates a state diagram of a media-editingapplication of some embodiments.

FIGS. 12-19 illustrate one example folder structure, as shown through afile navigation GUI.

FIG. 20 conceptually illustrates a process of some embodiments forcreating an asset data structure and a clip data structure referencingthat asset.

FIG. 21 conceptually illustrates an asset data structure for a videoasset, as well as an event data structure for an event that contains thevideo asset.

FIG. 22 conceptually illustrates a process of some embodiments forgenerating an asset ID and storing the ID in the data structure.

FIG. 23 illustrates a component clip data structure of some embodimentsthat references an asset.

FIG. 24 conceptually illustrates a nested sequence of clip objectscreated by the media-editing application of some embodiments for animported media file.

FIG. 25 conceptually illustrates the objects of FIG. 24 nested in aconceptual timeline.

FIG. 26 illustrates a timeline that includes four clips.

FIG. 27 conceptually illustrates a subset of the data structures for thesequence illustrated in FIG. 26.

FIG. 28 conceptually illustrates the objects of FIG. 27 nested in aconceptual timeline.

FIG. 29 conceptually illustrates a process of some embodiments forsearching for an asset.

FIG. 30 conceptually illustrates a process of some embodiments forresolving a missing asset.

FIG. 31 conceptually illustrates a state diagram for a media-editingapplication of some embodiments.

FIG. 32 illustrates the creation of a camera archive in four stages.

FIG. 33 illustrates the import of a set of media files from a cameraarchive over four stages.

FIG. 34 illustrates the file navigation GUI of some embodiments with thearchives folder selected.

FIG. 35 conceptually illustrates a process of some embodiments forpreparing images of a media file for one or more processingdestinations.

FIGS. 36 and 37 conceptually illustrate the software architecture of asystem of some embodiments.

FIG. 38 conceptually illustrates a process for determining which imageof a media file to display.

FIGS. 39 and 41 illustrate different clock mechanisms that are used bythe scheduling engine of some embodiments, depending on whether one ormore of the image destinations is a real-time destination or not.

FIG. 40 illustrates a timeline for the scheduling engine of someembodiments when the engine is scheduling operations for non-real-timedestinations.

FIG. 42 illustrates a timeline for the scheduling engine of someembodiments when the engine is scheduling operations for real-timedestinations.

FIG. 43 conceptually illustrates the software architecture of a systemthat enables dynamic modification of the output.

FIG. 44 conceptually illustrates a GUI of a media-editing applicationthat displays results of editing operations in the preview display areaas the editing operations are being performed.

FIG. 45 conceptually illustrates a process for incorporating edits intoplayback of a video sequence in real-time.

FIGS. 46-51 illustrate the use of the project library for various tasks,including creating a new project and restoring missing references in aproject.

FIG. 52 illustrates the user interface selection options of someembodiments for different levels of playback in a menu.

FIG. 53 conceptually illustrates the software architecture of a systemthat enables seamless transitioning between high- and low-resolutionediting.

FIG. 54 conceptually illustrates data structures for two differentimages.

FIG. 55 conceptually illustrates a process by which images are renderedat a first resolution then resampled for display at a differentresolution.

FIG. 56 conceptually illustrates a first resampling operation.

FIG. 57 conceptually illustrates a second resampling operation.

FIGS. 58 and 59 conceptually illustrate two different processes forrendering an image at full-size 1920×1080 when the image has animage-processing operation applied to it.

FIG. 60 conceptually illustrates a process of some embodiments forapplying an image processing operation to an image.

FIG. 61 illustrates a timeline as well as an output image.

FIG. 62 conceptually illustrates a scene graph that is converted to arender graph in order to render the image in FIG. 61.

FIG. 63 conceptually illustrates a process of some embodiments fordisplaying an image.

FIGS. 64 and 65 illustrate a workflow of some embodiments in which auser modifies the playback settings to use low-resolution media, andthen generates the low-resolution media so that it is available.

FIG. 66 conceptually illustrates a state diagram of some embodimentsrelating to the operation of background tasks for a media-editingapplication.

FIGS. 67 and 68 illustrate a user interface window that enables the userto view the progress of background tasks, pause and restart tasks, etc.

FIG. 69 conceptually illustrates a process of some embodiments fornormal operation of a task within the background task queue.

FIG. 70 conceptually illustrates the software architecture of a mediaediting application of some embodiments.

FIG. 71 conceptually illustrates an electronic system with which someembodiments of the invention are implemented.

DETAILED DESCRIPTION

In the following detailed description of the invention, numerousdetails, examples, and embodiments of the invention are set forth anddescribed. However, it will be clear and apparent to one skilled in theart that the invention is not limited to the embodiments set forth andthat the invention may be practiced without some of the specific detailsand examples discussed.

Some embodiments of the invention provide a media-editing applicationthat performs one or more destination operations on a media file (e.g.,video files, audio files, etc.) in parallel upon import of the mediafile. Rather than performing fully separate processing for eachoperation, the media-editing application performs certain imagepreparation operations (e.g., disk read, decode, format conversions)only once whenever possible, then sends the same image data to thedifferent destination operations.

FIG. 1 conceptually illustrates the software architecture of amedia-editing system 100 of some embodiments. Specifically, the figureillustrates the architecture relating to an import process performed bythe media-editing system 100. In some embodiments, some or all of thefunctions attributed to this system are performed by a media-editingapplication. In some embodiments, the media-editing application is anapplication that enables a user to create a composite media presentationfrom a set of media files. Through a graphical user interface (GUI) ofthe application, the user specifies the manner in which the media filesare composited to create the composite presentation. In addition,through this GUI, the user can command the application to import one ormedia files (e.g., from a camera, from an external drive, from aninternal drive, etc.).

As shown, the media-editing system 100 includes an import module 105, ascheduling engine 110, a disk reader 115, a decoder 120, an imageprocessor 122, and a set of image destinations 125. The system 100 alsoincludes media storage 130. In some embodiments, the media storage 130is a set of file folders organized by the media-editing application andstored on a particular set of storage devices. The storage devices mayinclude the boot drive of the electronic device on which the applicationoperates, a different partition of that disk, a separate internal orexternal hard drive, a flash drive, SD card, etc.

FIG. 1 also illustrates an external storage 135. The external storage135 is a storage device that stores media files that may be imported bythe media-editing application. The storage may be a camera, an SD card,a flash drive, an external hard drive, file storage of an internal harddrive separate from the organized file folder structure created by themedia-editing application, etc.

The import module 105 imports media files from the external storage 135.Upon instructions from the user (i.e., through the media-editingapplication GUI) or as an automatic response to the detection of themedia files in the external storage 135, the import module 105 copiesthe media files to a particular location in the media storage 130. Someembodiments create a particular folder within the folder structure ofthe media storage 130 for a set of imported media files (i.e., the mediafiles imported at a particular time) and store a copy of the importedfiles in this particular folder at time of import.

The disk reader 115 reads an image from a storage device (i.e., thestorage device on which the media storage 130 is located). In someembodiments, this represents a disk read operation (i.e., disk I/O call)performed by a processor of the computing system on which themedia-editing application is running. The decoder 120 performs a decodeoperation on an image retrieved by the disk reader 115, and may alsorepresent an operation performed by a processor of the computing system,or by a specific decoder hardware that is part of the system. In someembodiments, the image retrieved from the media storage is stored in anencoded format, while the destinations 125 require a set of unencodedpixel values that describe the image. Some embodiments are capable ofdecoding numerous different types of images, and will use the type ofdecoding required for the particular retrieved image.

The image processor 122 represents a set of operations that may beperformed on the image data to place the image data in the correctformat for each of the different destinations. The differentdestinations may want the image in different sizes (i.e., number ofpixels) and colorspaces in some embodiments, and thus the imageprocessor 122 may need to produce multiple different outputs for themultiple destinations. In some embodiments, these image-processingoperations may be performed by a primary processor (e.g., one or moreCPU cores) or a specialized graphics processing unit.

The destinations 125 are a set of operations the media-editingapplication performs on an image (in many cases, on each image of amedia file). In some embodiments, upon import of a media file, theimages of the media file are automatically sent to one or more of thedestinations for processing. At time of import, these destinations mayinclude encoding operations and analysis operations. Some embodimentsstore one or more versions of an imported media file in encoded formatsthat are particularly suitable for editing. For example, the applicationmight store a high-resolution encoded version and a low-resolutionencoded version of a media file, in addition to the original copy (whichmay also be encoded in a different format). In this example, imagedestination N is an encoding operation that stores its output (a newversion of a media file) into the media storage 130. The analysisoperations of some embodiments analyze the images of a media file todetermine specific information about the images. For instance, someoperations identify people in the images, identify time ranges in mediafiles captured by a shaking camera, balance color in the images, etc.The data from these analysis operations may be stored in a file (e.g.,in the media storage 130 or in separate folders) in some embodiments.

As stated, some embodiments perform these encoding and analysisoperations at time of import. With all of the operations being performedat once, the disk read and decode operations will only need to beperformed once for each image of an imported media file. In someembodiments, when a user indicates that he wants to import one or moremedia files, the application presents the user with a set of optionsthat enable the user to select operations for the application perform onthe imported media. These may include the high and low-resolutionencoding, the various video analysis operations mentioned above, as wellas audio analysis operations (e.g., identifying latent audio channels,identifying stereo pairs of channels, enhancing the audio, etc.). Whilemany of the video analysis and encoding operations are performed on eachimage of the media file, the audio operations may be performed on thefile as a whole or on each frame of audio (i.e., a portion of the audiohaving a particular length, which may correspond to the frame rate ofthe video).

In addition to performing the various image operations (e.g., encodingand analysis) at time of import, some embodiments can perform these andother operations post-import. Furthermore, video playback (and otherreal-time destinations that accompany playback) may be an additionalpost-import destination, as well as background rendering (i.e., thepreparation of output images for portions of a video sequence inadvance).

The scheduling engine 110 manages the performance of various operationson images of the media files in order to prepare those images for thedestinations 125. In some embodiments, the scheduling engine 110schedules disk reads (i.e., disk I/O calls), decodes, and imageprocessing operations. When the application is sending a media file tomultiple destinations (as shown in this figure), the engine willschedule only one disk read and one decode for each image in the mediafile. This prevents the performance of duplicative disk reads anddecodes. When all of the destinations require the image in the sameformat (i.e., the same size and colorspace), the scheduling engine willperform the conversions to this desired format only once as well. Whendifferent destinations need images in different formats, someembodiments will fan-out the operations as late as possible to minimizethe number of processing operations that need to be performed.

In some embodiments, the scheduling engine schedules operationsdifferently for real-time operations (e.g., playback) than fornon-real-time operations (e.g., analysis, encoding, etc.). For real-timeoperations, the most important factor in how fast to schedule images isto keep up with the display rate for the video. For instance, for 24frames per second (fps) video, the scheduling engine attempts to ensurethat images are being sent to the playback operation fast enough for acontinuous display of the video. When a clock in the scheduling engineindicates that the images are falling behind, the scheduling engine mayopt to skip (i.e., drop) images and schedule ahead so as to keep up withreal time. This also enables the media-editing application of someembodiments to modify its playback in real-time as the user edits acomposite presentation in the timeline.

On the other hand, for destinations such as an encoder, a colorbalancer, etc., it is more important to receive every image than toreceive the images at a particular rate. Thus, the scheduling engine ofsome embodiments will send images to these destinations based on whenthe destinations finish processing previous images as opposed to anyclock that correlates to actual time. That is, the scheduling enginebases the rate at which it schedules image preparation operations on theprocessing speed of the destination operations rather than a desiredframe rate.

When importing a media file, some embodiments create a media clip datastructure for the imported media that links to the media file, anytranscoded versions of the media file, and any analysis data about themedia file. This media clip is the entity that is added to a mediapresentation in some embodiments in order to include the media file (ora portion of the media file) in the composite presentation. FIG. 2conceptually illustrates such a media clip 200 of some embodiments. Themedia clip 200 includes source file metadata 205, a reference 210 to anoriginal media file 215, a reference 215 to a primary transcoded mediafile 225, a reference 230 to a secondary transcoded media file 235, areference (or references) 240 to generated clip data 245, and additionalclip data 250.

As will be described below, some embodiments actually store thisinformation in an asset data structure that specifically references themedia and analysis files, and then also create a clip data structurethat references the asset. FIG. 2 collapses this structure into a singlemedia clip for simplicity, while additional figures in Section I.Edescribe the data structures in further detail.

The source file metadata 205 may include, in some embodiments, suchinformation as a UUID for the media file generated by the camera thatcaptured the media, file format information, various video properties(e.g., frame rate, colorspace, pixel transform, dimensions, etc.), andvarious audio properties (e.g., channel count, track count, sample rate,etc.) of the media. The references 210, 220, and 230 to the originalmedia file 215 and transcoded media files 225 and 235 refer to theversions of the media file stored in the application's file storage.Some embodiments, for each set of imported media files, create separatefolders for the original media and any type of transcoded media. In someembodiments, the primary transcoded media and secondary transcoded mediaare high-resolution and low-resolution encodes of the original mediafile that may be created on import or post-import (e.g., by destinations125 of FIG. 1).

In some embodiments, these references to the files are pointers to thelocations of the files on the storage device. In some embodiments, themedia-editing application initially sets the reference 210 to theoriginal media such that the data structure references the media filethat is to be imported (e.g., the file or set of files on a camera—acamera may store multiple files that are imported as a single clip) asthe original media, then modifies this reference once the media file iscopied to the application's file storage so that the data structure nowreferences the media in the file storage. In some such embodiments, theapplication displays the media clips for the user to edit before thefile is actually copied. A user can begin creating a presentation withthe media clip while the clip refers to a file stored on a camera, thencontinue using the same clip once the file is copied with nointerruption to the editing workflow.

The generated clip data files 245, in some embodiments, are one or morefiles that store analysis data. For example, some embodiments store aperson detection file that stores information about the location ofpeople in each image of a video. Much like the folders for differentversions of media files, some embodiments create separate folders foreach type of analysis file within a folder for a set of imported files(e.g., a folder for person detection files, a folder for color balancefiles, a folder for shake detection files, etc.). In addition, someembodiments store additional clip data 250 in the media clip datastructure, as opposed to in a separate file. As one example, someembodiments store shake detection as a tag within the media clip thatreferences the media file or a specific portion of the media file.

Having data structures that refer to each of the different versions ofmedia enables the media-editing application of some embodiments toseamlessly switch between editing in high- and low-resolution. Referringto FIG. 1, when a user requests high-resolution editing, the schedulingengine 110 will instruct the disk reader 115 to read images from theoriginal media or the high-resolution transcoded media, whereas when auser requests low-resolution editing the engine instructs the diskreader to read images from the low-resolution transcoded media. Someembodiments attach a pixel transform to each image that specifies atransform of the image from an image space in which many editingoperations are defined into the pixel space of the image. Attaching thepixel transforms to the images in the image processing pipeline enablesediting operations to be defined independent of the size and type ofimages being received, and thus makes possible the seamless transitionbetween using high- and low-resolution files for editing.

As mentioned, for each imported media file, some embodiments create bothan asset data structure that stores references to the different versionsof the imported media file and a clip data structure that refers to theasset. Some embodiments create a nested series of clip structures forthe imported file, including a first clip structure that refers to theasset and a second clip structure that contains the first clipstructure. The second clip structure may be contained within a datastructure that stores several associated clips and assets. When a useradds the media clip to a composite presentation, some embodimentsduplicate the first and second clip structures and add these structuresto a data structure for the composite presentation.

In the course of editing, projects will be unable to identify theunderlying media from time to time. An asset might be deleted, an assetmight exist but reference a file that no longer exists, etc. Someembodiments provide various mechanisms to modify the clip or projectreferences in order to restore the media in the project (e.g., finding adifferent asset in the application that refers to a copy of the samemedia file).

In addition, some embodiments allow a user to create archives of themedia on a camera in a bundle from which the files can be laterimported. If a user deletes all of the media (i.e., to save disk space),the user can restore this media from camera archives and the applicationwill be able to identify the media files (using a file identifier suchas a UUID) and restore its missing references.

Several more detailed embodiments of the invention are described in thesections below. Section I describes various aspects of importing mediawith a media-editing application, including the parallel processing ofthe media, the creation of data storage structures for the media, andother topics. Section II describes a playback engine, or schedulingengine, that facilitates parallel processing of media clips, bothpre-import and post-import. Section III describes the use of theplayback engine to encompass edits into playback in real time. SectionIV then describes the project library of some embodiments and cliprecovery. Next, section V describes switching between high- andlow-resolution editing according to some embodiments. Section VI thendescribes background task monitoring. Section VII describes the softwarearchitecture of a media-editing application of some embodiments.Finally, Section VIII describes an electronic system that implementssome embodiments of the invention.

I. Importing Media

As mentioned above, the media-editing application of some embodimentsperforms operations on media files (e.g., video files, audio files,movie files with both video and audio tracks, etc.) in order to create acomposite presentation. In order for the media-editing application toaccess the media, some embodiments provide an import procedure forimporting media into the application. Some embodiments import media intoa specific set of file folders defined for the application on a physicalstorage device connected to (or part of) the device on which theapplication operates (e.g., a hard drive of a computer on which theapplication operates).

While importing media, some embodiments perform a set of operations inparallel to create additional versions of the media, analyze the media,etc., as described above. In some embodiments, a user of themedia-editing application may select which of the operations theapplication should perform during import. These operations may includetranscoding the media (e.g., creating high and/or low-resolutionversions of the media that are easy to edit), performing image analysis(e.g., finding people in images, detecting shaky video, balancing color,etc.), and performing audio analysis (e.g., identifying latent audiochannels, identifying mono channels and stereo pairs, enhancing audio,etc.).

In addition to storing the actual media files (and any transcodedversions of the media), some embodiments define a media clip for eachpiece of imported media and store this media clip as data associatedwith the media-editing application. The media clip of some embodimentsincludes references to the one or more versions of the media file,metadata about the media file, references to any analysis data about themedia file, etc.

The following subsections include detailed description of variousaspects of the import process. Subsection A provides a description ofthe user interface of some embodiments through which a user importsmedia into the media-editing application, and subsection B describes theparallel processing on import. Next, subsection C describes the abilityto edit a media clip before its media file is actually imported by themedia-editing application. Subsection D then describes the folderstructure into which the media is stored, while Subsection E describesthe clip structure of some embodiments. Subsection F describes a cameraarchives feature of some embodiments that allows a user to create anarchive of media from a camera or other external device.

A. User Interface for Importing Media

As mentioned, some embodiments enable a user to import media through auser interface of the media-editing application. The user can selectwhich media to import (from a device such as a camera, an externaldrive, internal drive, etc.) and what should be done with the media uponits import. In addition, during and after import, the user interface(UI) makes available the media clips corresponding to the imported filesso that the user can use these media clips to create a compositepresentation.

FIG. 3 illustrates a graphical user interface (GUI) 300 of amedia-editing application of some embodiments. One of ordinary skillwill recognize that the graphical user interface 300 is only one of manypossible GUIs for such a media-editing application. In fact, the GUI 300includes several display areas which may be adjusted in size, opened orclosed, replaced with other display areas, etc. The GUI 300 includes aclip library 305, a clip browser 310, a timeline 315, a preview displayarea 320, an inspector display area 325, an additional media displayarea 330, and a toolbar 335.

The clip library 305 includes a set of folders through which a useraccesses media clips that have been imported into the media-editingapplication. Some embodiments organize the media clips according to thedevice (e.g., physical storage device such as an internal or externalhard drive, virtual storage device such as a hard drive partition, etc.)on which the media represented by the clips are stored. Some embodimentsalso enable the user to organize the media clips based on the date themedia represented by the clips was created (e.g., recorded by a camera).As shown, the clip library 305 includes media clips from both 2009 and2011.

Within a storage device and/or date, users may group the media clipsinto “events”, or organized folders of media clips. For instance, a usermight give the events descriptive names that indicate what media isstored in the event (e.g., the “Wedding” event shown in clip library 305might include video footage from a wedding). In some embodiments, themedia files corresponding to these clips are stored in a file storagestructure that mirrors the folders shown in the clip library.

Within the clip library, some embodiments enable a user to performvarious clip management actions. These clip management actions mayinclude moving clips between events, creating new events, merging twoevents together, duplicating events (which, in some embodiments, createsa duplicate copy of the media to which the clips in the eventcorrespond), deleting events, etc. In addition, some embodiments allow auser to create sub-folders of an event. These sub-folders may includemedia clips filtered based on tags (e.g., keyword tags). For instance,in the wedding event, all media clips showing the bride might be taggedby the user with a “bride” keyword, and then these particular mediaclips could be displayed in a sub-folder of the wedding event thatfilters clips in the wedding event to only display media clips taggedwith the “bride” keyword.

The clip browser 310 allows the user to view clips from a selectedfolder (e.g., an event, a sub-folder, etc.) of the clip library 305. Asshown in this example, the folder “New Event 2-8-11 3” is selected inthe clip library 305, and the clips belonging to that folder aredisplayed in the clip browser 310. Some embodiments display the clips asthumbnail filmstrips, as shown in this example. By moving a cursor (or afinger on a touchscreen) over one of the thumbnails (e.g., with a mouse,a touchpad, a touchscreen, etc.), the user can skim through the clip.That is, when the user places the cursor at a particular horizontallocation within the thumbnail filmstrip, the media-editing applicationassociates that horizontal location with a time in the associated mediafile, and displays the image from the media file for that time. Inaddition, the user can command the application to play back the mediafile in the thumbnail filmstrip.

In addition, the thumbnails for the clips in the browser display anaudio waveform underneath the clip that represents the audio of themedia file. In some embodiments, as a user skims through or plays backthe thumbnail filmstrip, the audio plays as well.

Many of the features of the clip browser are user-modifiable. Forinstance, in some embodiments, the user can modify one or more of thethumbnail size, the percentage of the thumbnail occupied by the audiowaveform, whether audio plays back when the user skims through the mediafiles, etc. In addition, some embodiments enable the user to view theclips in the clip browser in a list view. In this view, the clips arepresented as a list (e.g., with clip name, duration, etc.). Someembodiments also display a selected clip from the list in a filmstripview at the top of the browser so that the user can skim through orplayback the selected clip.

The timeline 315 provides a visual representation of a compositepresentation (or project) being created by the user of the media-editingapplication. Specifically, it displays one or more geometric shapes thatrepresent one or more media clips that are part of the compositepresentation. The timeline 315 of some embodiments includes a primarylane (also called a “spine”, “primary compositing lane”, or “centralcompositing lane”) as well as one or more secondary lanes (also called“anchor lanes”). The spine represents a primary sequence of media which,in some embodiments, does not have any gaps. The clips in the anchorlanes are anchored to a particular position along the spine (or along adifferent anchor lane). Anchor lanes may be used for compositing (e.g.,removing portions of one video and showing a different video in thoseportions), B-roll cuts (i.e., cutting away from the primary video to adifferent video whose clip is in the anchor lane), audio clips, or othercomposite presentation techniques.

The user can add media clips from the clip browser 310 into the timeline315 in order to add the clip to a presentation represented in thetimeline. Within the timeline, the user can perform further edits to themedia clips (e.g., move the clips around, split the clips, trim theclips, apply effects to the clips, etc.). The length (i.e., horizontalexpanse) of a clip in the timeline is a function of the length of mediarepresented by the clip. As the timeline is broken into increments oftime, a media clip occupies a particular length of time in the timeline.As shown, in some embodiments the clips within the timeline are shown asa series of images. The number of images displayed for a clip variesdepending on the length of the clip in the timeline, as well as the sizeof the clips (as the aspect ratio of each image will stay constant).

As with the clips in the clip browser, the user can skim through thetimeline or play back the timeline (either a portion of the timeline orthe entire timeline). In some embodiments, the playback (or skimming) isnot shown in the timeline clips, but rather in the preview display area320.

The preview display area 320 (also referred to as a “viewer” displaysimages from media files that the user is skimming through, playing back,or editing. These images may be from a composite presentation in thetimeline 315 or from a media clip in the clip browser 310. In thisexample, the user has been skimming through the beginning of clip 340,and therefore an image from the start of this media file is displayed inthe preview display area 320. As shown, some embodiments will displaythe images as large as possible within the display area whilemaintaining the aspect ratio of the image.

The inspector display area 325 displays detailed properties about aselected item and allows a user to modify some or all of theseproperties. The selected item might be a clip, a composite presentation,an effect, etc. In this case, the clip that is shown in the previewdisplay area 320 is also selected, and thus the inspector displaysinformation about media clip 340. This information includes duration,file format, file location, frame rate, date created, audio information,etc. about the selected media clip. In some embodiments, differentinformation is displayed depending on the type of item selected.

The additional media display area 330 displays various types ofadditional media, such as video effects, transitions, still images,titles, audio effects, standard audio clips, etc. In some embodiments,the set of effects is represented by a set of selectable UI items, eachselectable UI item representing a particular effect. In someembodiments, each selectable UI item also includes a thumbnail imagewith the particular effect applied. The display area 330 is currentlydisplaying a set of effects for the user to apply to a clip. In thisexample, only two effects are shown in the display area (the keyereffect and the luma keyer effect, because the user has typed the word“keyer” into a search box for the effects display area).

The toolbar 335 includes various selectable items for editing, modifyingwhat is displayed in one or more display areas, etc. The right side ofthe toolbar includes various selectable items for modifying what type ofmedia is displayed in the additional media display area 330. Theillustrated toolbar 335 includes items for video effects, visualtransitions between media clips, photos, titles, generators andbackgrounds, etc. In addition, the toolbar 335 includes an inspectorselectable item that brings causes the display of the inspector displayarea 325 as well as items for applying a retiming operation to a portionof the timeline, adjusting color, and other functions.

The left side of the toolbar 335 includes selectable items for mediamanagement and editing. Selectable items are provided for adding clipsfrom the clip browser 310 to the timeline 315. In some embodiments,different selectable items may be used to add a clip to the end of thespine, add a clip at a selected point in the spine (e.g., at thelocation of a playhead), add an anchored clip at the selected point,perform various trim operations on the media clips in the timeline, etc.The media management tools of some embodiments allow a user to markselected clips as favorites, among other options.

In addition, the media-editing application includes an import initiationitem 345, which includes a camera icon in this figure. As shown, when auser holds the cursor over the item 345, the application displaysfeedback saying “Import from Camera” in the GUI 300. As shown, the useris selecting this item with a cursor in FIG. 3. This selectionoperation, as well as other user interface operations shown with acursor throughout this application, could be performed with a cursorcontroller such as a mouse, touchpad, trackpad, etc. Furthermore, one ofordinary skill will realize that these user interface operations shownas performed by a cursor could also be performed through a touchscreen,which may not have a cursor. In addition, while the import process (andother processes in this application) are shown as initiated throughvarious items in the user interface (e.g., item 345), many of theseoperations may be initiated in ways other than those shown, such asthrough drop-down or other menus, keystrokes, etc.

One or ordinary skill will also recognize that the set of display areasshown in the GUI 300 is one of many possible configurations for the GUIof some embodiments. For instance, in some embodiments, the presence orabsence of many of the display areas can be toggled through the GUI(e.g., the inspector display area 325, additional media display area330, and clip library 305). In addition, some embodiments allow the userto modify the size of the various display areas within the UI. Forinstance, when the display area 330 is removed, the timeline 315 canincrease in size to include that area. Similarly, the preview displayarea 325 increases in size when the inspector display area 325 isremoved.

FIG. 4 illustrates the import process of some embodiments in four stages410-440. Stages 410-430 illustrate an import display area 400 displayedby the media-editing application as a result of the selection of theimport initiation item 345 or a similar GUI feature (e.g., a drop-downor other type of menu option, a different selectable GUI item, etc.),and through which the import process is performed, while stage 440illustrates the clip library 305 and clip browser 310 after the importprocess. In some embodiments, the import display area 400 is displayedas a moveable window over a portion of the GUI 300.

The import display area 400 includes a device selection area 405, amedia browser 415, a preview area 425, and a set of user-selectableitems 435. The device selection area 405 includes a set of cameras and aset of camera archives from which the user may select to import mediainto the media-editing application. In some embodiments, camerasdetected by the media-editing application may include cameras with harddrives, cameras with SD cards, digital tape-based cameras, SD cards (orsimilar physical storage devices) separated from their cameras, etc.Camera archives are described in further detail below in subsection F ofthis section.

The media browser 415 displays media files (or sets of media files)identified on a device (e.g., on a camera). In some cases, what themedia-editing imports as a single file may not be stored as such on thecamera. For instance, a file imported as a single movie file might bestored on the camera as a video file, multiple audio files, and ametadata file. The nature of the camera's storage may depend on the typeof camera; for instance, smaller consumer cameras may store a singlefile whereas a professional camera will have a more sophisticated set ofvideo, audio, and metadata files. Throughout this application, thesecollections of files may be referred to as a media file on a camera.

In some embodiments, the media-editing application displays the mediafiles in a manner similar to the media clips in clip browser 310. Thatis, the user can skim or playback the media files while the files arestill stored on the storage device and not yet imported. The previewarea 425 displays previews of the media files on the device as the userskims or plays back the media files. As shown, the preview area 425includes a set of playback controls (e.g., play and stop buttons, fastforward and rewind buttons, etc.). The set of user selectable items 435includes various selectable items that enable a user to import media,create camera archives, and access camera archives. Camera archives willbe described in further detail in subsection F below.

As shown at stage 410 of FIG. 4, the user has moved the cursor over theselectable item 445 for camera VPC-GH4, and is in the process ofselecting this particular camera. The second stage 420 shows that withthe camera VPC-GH4 selected, the media files on that camera now populatethe media browser 415. In this case, there are three media files thatappear as thumbnails in the media browser 415, one of which is alsoshown in the preview area 425. The stage 420 also shows the userselecting selectable item 450, labeled “Import All”. As shown, the setof user selectable items 435 also includes an item “Import Selected”.The import all button allows a user to import all files from a selecteddevice or archive, while the import selected button allows the user toimport files selected in the media browser 415. In some embodiments,there is only one import button, which imports all files as a default,but only imports selected files when the user has selected one or morefiles in the media browser.

The third stage 430 illustrates an import dialog box 455 that presentsthe user with a number of options for analyzing the incoming media. Insome embodiments, the dialog box also includes a list of media filesfrom which the user may choose files to import. In other embodiments,the user has already made this selection (by selecting to import allfiles from a device or a subset of the files on the device) as describedabove. Some embodiments allow a user to import files that are alreadystored on the device on which the application operates, in which casethe application displays a similar dialog box that also includes a filebrowser section.

As shown, the import dialog box 455 allows a user to either add theimported files to an existing event or create a new event for theincoming media. When creating a new event, the user can select thedevice on which the event should be created. As described above, anevent is a folder of media clips that a user has chosen to grouptogether (e.g., because the clips were all shot at the same time andplace, the clips all relate to a particular topic, etc.). In someembodiments, the media-editing application stores all events in aparticular section of the file storage of a device, for organizationpurposes. In this case, the user has selected to create a new event,“Event 3”, which will be saved on the Macintosh HD (i.e., the hard driveof the device on which the media-editing application operates).

The import dialog box also includes a number of checkboxes for variousoptimization and analysis options. In some embodiments, as shown, theseare broken down into four groups: organizing, transcoding, videoanalysis, and audio analysis. The organization options include a firstoption for copying files to the Events folder, and a second option forimporting folders as keyword collections. The first option copies theimported media files to a specific folder for original media in theEvents folder on the selected device or drive. The second option importsfolders of the selected import device (e.g., the camera) as keywordcollections. That is, when the selected camera has media organized intofolders, the media-editing application tags the media clips in the eventwith the name of the folder. A user can then view the clips in the eventfiltered by keywords, in some embodiments.

The transcoding and analysis options are options for various actionsthat can be taken on the imported media files. In some embodiments,these actions are all performed in an efficient manner using parallelprocessing, as described in subsection B below. Two transcode optionsare provided: create optimized media, and create proxy media. In someembodiments, the optimized media is a high-resolution transcode of theoriginal media file and the proxy media a low-resolution transcode ofthe original media file. These different versions of the media file arestored in the event folder in some embodiments, and used to enable themedia-editing application to seamlessly switch between high- andlow-resolution editing.

In some embodiments, the optimized media is generated at the sameresolution as the original imported media, but is in a format bettersuited for editing. Whereas the original media may have significanttemporal dependencies in the encoding (i.e., one image in the videosequence is encoded by reference to numerous other images in the videosequence) depending on the format of the media, the optimized media usesa format without such temporal compression. In some embodiments, theoptimized format uses ProRes 422 encoding. This simplifies the editingprocess, as often a user will only want to use some of the images in amedia file, and when each image in a video sequence can be decoded anddisplayed on its own, the retrieval of a specific one of the images issimplified (i.e., does not require the retrieval or decode of any otherimages). As described below, some embodiments automatically determinewhether imported media should include an optimized transcode based onthe format of the media. In fact, some embodiments automatically selectthe checkbox for optimized media when the format is not well suited forediting (e.g., AVCHD format, in which often only one in a large group ofimages (e.g., 15 or 30) is encoded without reference to other images).On the other hand, some embodiments either gray out the optimized mediacheckbox or do not create the optimized media even if the checkbox isselected in the case that the imported media is in a format that isalready easy to use for editing (e.g., the iFrame format or DV, whichinclude no temporal compression).

The proxy media, in some embodiments, is also designed for editing, butstores images at a lower resolution. Some embodiments use the ProResProxy format, which stores images at a resolution of 960×540 (i.e.,one-fourth the size of the optimized media). In some embodiments, theoptimized and proxy versions of the media files are stored in specificfolders within an event folder on the storage, as described below.

The video analysis options of some embodiments, as shown in dialog box455, include identification of image stabilization problems, automaticcolor balancing, and person detection. The image stabilization operationof some embodiments identifies portions of the video in a media file inwhich the camera appears to be shaking, and tags the media file (or aportion of the media file with the shaky video) with a term such as“shake”. Users can then search in the clip browser for clips with the“shake” tag and perform shake correction on these clips. Otherembodiments automatically perform the shake correction when the shake isdetected. In addition, some embodiments store an image stabilizationfile for each media clip analyzed that may indicate dominant motion(e.g., determined by computing motion vectors for the images) betweenthe images and how to invert this motion in order to cancel the shake.

The color balancing of some embodiments automatically balances the colorof each image in a media file and saves the color balancing informationin a color balance file for each media file analyzed. The colorbalancing operation adjusts the colors of an image to give the image amore realistic appearance (e.g., reducing tint due to indoor lighting).Different embodiments may use different color balancing algorithms.

The person detection algorithm identifies locations of people in theimages of a media file and saves the person identification informationin a person detection file for each media file analyzed. The persondetection operation of some embodiments identifies faces using a facedetection algorithm (e.g., an algorithm that searches for particulargroups of pixels that are identified as faces, and extrapolates the restof a person from the faces). Some embodiments provide the ability todifferentiate between single people (e.g., in an interview shot), pairsof people, groups of people, etc. In addition to, or instead of, savinga person detection file, some embodiments tag the media clip created forthe media file with a tag (e.g., a keyword tag) that indicates that theclip includes people in a particular range. Other embodiments usedifferent person detection algorithms.

As described in detail below, some embodiments process each image of amedia file in an efficient manner by performing all of the optimizationand analysis in parallel. That is, each image is read from a disk onlyonce and decoded only once, then sent to each of the various operations(e.g., the transcoding and analysis operations). In some embodiments,the same engine that is used to prepare images for playback alsoprepares images for the transcoding and analysis operations.

In addition to the video operations, some embodiments include audioanalysis operations at import as well. As shown, these operations mayinclude analysis for audio problems, separation of mono audio channelsand identification of stereo pairs, and removal of latent audio channels(i.e., channels of audio that are encoded in the imported file or set offiles but do not include any actual recorded audio). Other embodimentsmay make available at import additional or different audio or videoanalysis operations, as well as additional transcode options.

The third stage 430 of FIG. 4 illustrates that the user is selecting theimport selectable item 460 in order to start the import process. Thissets off a process that creates a clip for each media file, copies themedia file, and performs all of the requested analysis and transcodingoperations on the media file. The creation of media clips will bedescribed in detail below in subsection E of this section.

The fourth stage 440 illustrates the clip library 305 and clip browser310 from GUI 300 of FIG. 3 after the import operation. In FIG. 3, the“2009” folder of clip library 305 included two events. At stage 440 ofFIG. 4, the clip library now includes a third event in the “2009”folder, the newly created “Event 3”. As these are placed in the 2009folder, the media files in the event were created (i.e., filmed) in theyear 2009. In fact, as can be seen by viewing the thumbnail filmstripsin the clip browser 310, some of the clips are the same as in “New Event2-8-11 3”. At this point, the media clips have been created, and thecopying of the original media, transcoding, and analysis may or may nothave been completed. These tasks take place in the background in someembodiments, while the user can work with the clips (e.g., add the clipsto the timeline) as soon as the clips are created.

As mentioned in the preceding discussion, some embodiments automaticallydetermine whether or not the media-editing application should perform ahigh-resolution transcode of a media file during import. To make thisdetermination, the media-editing application examines the format of themedia files. FIG. 5 conceptually illustrates a process 500 of someembodiments for determining whether or not to recommend ahigh-resolution transcode to the user.

As shown, the process 500 begins by identifying (at 505) the format ofan incoming media file. In some embodiments, the media editingapplication determines the format by reading metadata in the media file(or in a metadata file associated with the media file or files).Examples of formats include AVCHD, iFrame, AVC-Intra, etc.

The process then determines (at 510) whether the media file is encodedin a format suitable for editing. In some embodiments, the media-editingapplication determines that a media file is in a format suitable forediting when each video image in the media file is encoded withoutreference to any other images, as opposed to formats that use temporalcompression. For instance, the iFrame format does not use temporalcompression, and therefore there is no reason to create ahigh-resolution transcode of an iFrame video, as the iFrame video iseasy to edit. On the other hand, AVCHD often has one image every fifteenor thirty that is encoded without reference to any other images, whilethe rest of the images are encoded by reference to at least one otherimage.

When the media file is encoded in a format suitable for editing, theprocess recommends (at 515) only a low-resolution transcode for themedia file. Otherwise, the process recommends (at 520) both alow-resolution transcode and a high-resolution transcode for the mediafile. The process then ends. In some embodiments, the media-editingapplication makes this recommendation by either automatically checking acheckbox such as that shown in stage 430 of FIG. 4, or by graying outsuch a checkbox. Some embodiments simply do not perform ahigh-resolution transcode of a media file that is already in a formatoptimized for editing, as such a file will take up disk space and notprovide any advantages over the original format of the media file.

FIG. 6 illustrates an example of a situation in which the media-editingapplication would generate both a high-resolution and a low-resolutiontranscode of a media file. In this case, the original media 600 isencoded in a temporally compressed manner, in which every fifteenthframe is an intraframe (i.e., a video image that is encoded withoutreference to other images in the sequence). The other intermediateframes are predictive or bidirectional frames, that are encoded byreference to one or more other images. The media-editing applicationcreates a high-resolution transcode 605 for these images and alow-resolution transcode 610 (shown as one-fourth the size of theoriginal media). In both of these transcoded versions, all of the imagesare intraframes, encoded without temporal compression.

FIG. 7, on the other hand, illustrates an example of a situation inwhich the media-editing application would generate only a low-resolutiontranscode of a media file. In this case, the original media 700 isencoded without temporal compression, so that all of the images areencoded without reference to other images. The media-editing applicationonly creates a low-resolution transcode 705, which (as above) isone-fourth the size of the original media. While the low-resolutiontranscodes are shown as having one fourth the size of the original(i.e., half the height and half the width), one of ordinary skill in theart will recognize that different embodiments might use different sizesfor the various forms of media (e.g., having a low-resolution version ofthe media that is two-thirds the height and width of the original media,or creating more than two sizes of media).

B. Media Import Process

As mentioned above, some embodiments perform processing of multipleoperations upon import. Either automatically or based upon userselection, the media-editing application will perform a file copyoperation, transcoding operations, and media analysis operations. Insome embodiments, the application first performs a file copy operation,then begins performing the transcoding and media analysis operations inan efficient manner. In other embodiments, the application begins thetranscoding and analysis operations as soon as the import begins byreading the media file from the external device (e.g., camera), thenswitching to use the imported file once that file is created.

FIG. 8 conceptually illustrates a process 800 of some embodiments forimporting media with a media-editing application. In some embodiments,the process is performed in response to a user command (e.g., through auser interface) to import the media file. Some embodiments, though,automatically import files from a device such as a camera when thedevice is attached to the computer or similar device on which theapplication operates, and the application is running.

As shown, the process 800 begins by receiving (at 805) a command toimport a media file from a device. As mentioned, the import may be theresult of a user instructing the application to import a file from thedevice. The device might be an external device such as a digital videocamera, an external drive (e.g., an external hard drive, a flash drive,an SD card, etc.), or a drive internal to the device on which theapplication operates (e.g., the same hard drive, a different partitionof the hard drive, etc.). In the latter case, the media file might belocated in a folder, on the same hard drive as the imported files, thatis not associated with the media-editing application.

The process then creates (at 810) an asset data structure for the mediafile and includes a reference to the media file in the asset datastructure. At this stage, the reference to the media file is a referenceto the file stored external to the application's folder structure (e.g.,the file on the camera, on an external drive, etc.). The asset datastructure will be explained in more detail below in subsection E of thissection. Some embodiments import each media file as an asset and createa data structure for the asset that references the media file and storesadditional data. The application then uses clip data structures thatinclude references to one or more assets and store the relation betweenthe assets in the clip structure. The asset data structure of someembodiments, in addition to storing a reference to the media file,stores references to transcoded versions of the media file and toanalysis data about the media file. In addition to creating the assetdata structure, some embodiments also create a clip data structure atthe same time that references the asset.

After creating the asset data structure, the process receives (at 815)the media file from the device (e.g., the camera). As mentioned, theasset data structure initially refers to the media file stored on thisdevice, which allows the user to perform edits with the media clip forthat asset before the file is copied over to the application filestorage.

The process then stores (at 820) the original copy of the media file inthe application storage (e.g., one or more file folders organized by theapplication for storing media) and modifies the reference to the file inthe asset data structure. That is, once the media file has been fullycopied to the application folder, the application modifies the assetdata structure to refer to the file in the application's folderstructure, rather than the file on the camera (or other device).

Next, the process 800 receives (at 825) a set of operations to performon the media file. As mentioned above, in some embodiments themedia-editing application performs the analysis on the media file oncethe media file is copied over to the application file storage. The setof operations of some embodiments includes the transcoding operationsand analysis operations that are mentioned above—these may include high-and low-resolution transcodes, video analysis (e.g., person detection,color balancing, shake detection), and audio analysis (e.g., audiodefect correction, mono/stereo detection, and latent channel detection).As shown, the user may determine which of these operations should beperformed by selecting from a list of operations at the time of import.Some embodiments perform a set of operations automatically, and theparticular operations performed may depend on the type of file beingimported.

In some embodiments, the media-editing application may also provide anoption for performing any of these operations at some time after importas well. For example, if the user is on a laptop computer out in thefield, they may not want to perform all of the analysis (or any of theanalysis) on the laptop, as the laptop may not have the processingcapability to perform all of the analysis while still running smoothly.Upon returning to a desktop computer with significant processing power(and storage space for transcoded files), the user could then have theapplication perform the analysis and transcode operations.

Based on the set of operations to perform, the process determines (at830) whether to perform a high-resolution encoding operation to create ahigh-resolution encoded file. As mentioned, in some embodiments, thehigh-resolution transcoded media is encoded in ProRes 422 format, at1920×1080 resolution. In addition, as described above, some embodimentsonly generate this encoded file when the original media file is in aformat that is not suited for easy editing, such as when most of thevideo images are temporally compressed.

When the editing application is performing a high-resolution encodingoperation, the process creates (at 835) a high-resolution transcodedversion of the media file in the file storage for the application. Thehigh-resolution transcoded media file will at this point not yet becomplete with all of the video images, as each of these images must beencoded and stored in the file by the high-resolution encoder.

The process also determines (at 840) whether to perform a low-resolutionencoding operation to create a low-resolution encoded file. Asmentioned, in some embodiments, the low-resolution transcoded media isencoded in ProRes Proxy format, at 960×540 resolution (which isone-fourth the number of pixels of the high-resolution transcodedmedia). As described above, some embodiments leave it up to the userwhether or not to generate a low-resolution encode.

When the editing application is performing a low-resolution encodingoperation, the process creates (at 845) a low-resolution transcodedversion of the media file in the file storage for the application. Thelow-resolution transcoded media file will at this point not yet becomplete with all of the video images, as each of these images must beencoded and stored in the file by the low-resolution encoder. In someembodiments, the application also stores a reference to the newlycreated files in the asset data structure for the imported media file.

With the original file copied over to the file storage for theapplication, the process can begin the parallel processing operations onthe media file for generating the transcoded file(s) and performing thevideo and audio analysis. The process selects (at 850) an image of theoriginal media file. In some embodiments, the media-editing applicationaccesses the images in the order of the video sequence (i.e., intemporal order of the video).

With the image selected, the process reads (at 855) the selected imagefrom the disk on which it is stored (e.g., the hard drive of the deviceon which the application is operating). In some embodiments, asdescribed in detail below in Section B, this involves scheduling a diskread operation with a processor of the device. The disk read operationaccesses the media file and reads the data from the media file thatdescribes the selected image. Some embodiments store this data involatile memory, such as RAM, or in a cache of the processor.

The process 800 then decodes (at 860) the data that has been read fromthe disk to arrive at a description of the image. In some embodiments,the image description includes a pixel buffer. The pixel buffer of someembodiments is an ordered set of pixels, where each pixel includes a setof coordinates (i.e., where in the image the pixel is located) and a setof pixel values that describes the pixel (e.g., color values in aparticular colorspace). As described below in Section V, someembodiments include additional detail in the image, such as a pixeltransform and a colorspace in which the pixels are defined.

With the image decoded, the process sends (at 865) the decoded image toall of the required operations (i.e., the operations received at 825).As noted, these operations may include one or more transcodingoperations, analysis operations such as person detection, colorbalancing, shake detection, and audio operations, etc.). As shown, theprocess only reads each image once and decodes the image once, asopposed to performing a separate read and decode for each destinationoperation. This enables more efficient processing of the media file. Aswill be described in further detail in Section II, the process of someembodiments may additionally perform a number of format conversionsbefore sending each image to its destination operations (e.g.,colorspace conversions, size conversions, etc.). Each operation may wanta particular format image, and thus the images will need to be convertedto the appropriate format for each operation.

After sending the currently selected image to the required operations,the process 800 determines (at 870) whether any more images remain inthe media file. The media-editing application will perform the requiredanalysis on each image by reading the image data from the disk, decodingthe image data, and sending the image to the appropriate operations.When additional images remain, the process returns to 850 to select thenext image.

Once all images are analyzed and transcoded, the process modifies (at875) the asset data structure to include references to any transcodedversions of the media file and any analysis data for the media file. Theprocess then ends. The references stored in the asset data structurewill be described in further detail below in subsection E.

One of ordinary skill in the art will recognize that the process 800 isa conceptual process, and that the operations may not be performed inthe specific order described. For instance, the process may perform manyof the operations at the same time or in an overlapping manner (e.g.,creating the high and low res transcoded versions of the media file andcreating references to those media files in the asset data structure).In addition, the disk reads and decodes may not be performed in theorderly fashion shown in process 800—instead, the process may performdisk reads and decodes ahead of time (e.g., reading image 2 from a diskbefore the processing of image 1 is complete).

As described, the media-editing application of some embodiments firstcopies the original media file to a particular file folder associatedwith the application and then performs the transcoding and analysis onthe copied version of the original media file. As opposed to performingthe transcode and analysis operations on the media file stored on anexternal device (such as a camera), this enables the user to quicklydisconnect the external device once the files are all copied. Forexample, the user could connect a camera with a number of video clips toa computer, quickly copy that video to the computer, then disconnect thecamera and continue shooting video while the computer transcodes andanalyzes the video and another user edits the video into a compositepresentation.

FIG. 9 illustrates this situation in two stages 910 and 920. At stage910, a camera 905 is connected to a computer 915. An original media file925 is stored on the camera 905, having been captured by the camera 905.In response to a user import command (e.g., as shown in FIG. 4), thecamera begins transferring the media file 925 to the computer 915). Atstage 920, the camera 905 has been disconnected from the computer 915.The original media file 925 remains on the camera (although the user maychoose to delete this file), but a second copy 930 of the media file isnow stored on the computer 915. As shown, although the camera 905 isdisconnected, the computer is generating a transcoded media file 940from the original media file 930.

As described by reference to FIG. 1 and FIG. 8, some embodiments sendeach image of an imported media file to multiple destinations inparallel. FIG. 1 illustrated that a disk reader reads image data from amedia storage and sends the data to a decoder, which then sends thedecoded image to a number of destinations. FIG. 10 illustrates a system1000 with examples of specific destinations to which the decoder maysend decoded images, as well as the output of those destinations.

As with FIG. 1, the system 1000 includes an external storage 1005, animport module 1010, a media storage 1015, a disk reader 1020, a decoder1025, and a scheduling engine 1030. The system 1000 also includes a userinterface 1035 and image destinations 1040-1065. The external storage1005 is a storage external to the file structure of the media editingapplication. This storage may be a storage on an external camera (e.g.,a digital tape, a hard drive, an SD card, etc.), a storage on anexternal drive such as a flash drive, external hard drive, SD cardisolated from a camera, etc.), or even on the same disk as theapplication's file storage (i.e., the same partition or a differentpartition of the disk).

A user interacts with the media-editing application through userinterface 1035. As shown in FIGS. 3 and 4, the user can select whichmedia files to import and what operations should be performed on themedia files through the user interface. The user interface 1035instructs the import module 1010 as to which files from the externalstorage 1005 should be imported.

The import module 1010 receives instructions from the user interface1035 indicating which files from the external storage 1005 to import.Based on these instructions, the import module 1010 copies the indicatedfiles from the external storage 1005 to the media storage 1015. In someembodiments, the import module creates any required folders in the filefolder structure for the application (e.g., an events folder, folderswithin the events folder for the original media file, transcoded media,analysis files, etc.). In some embodiments, the import module (or adifferent module) creates the asset and clip data structures for theimported file. The media storage 1015, as mentioned, stores the importedmedia file, and may represent a set of file folders in the file storageof either the device (i.e., the boot disk of the device) on which theapplication operates or a different storage device.

The disk reader 1020 reads image data from the appropriate media file inthe media storage 1015, as instructed by the scheduling engine 1030, andpasses the image data to the decoder 1025. Unless the image data is in araw, unencoded format, the data needs to be decoded in order for adestination to work with the image. Thus, the decoder 1025 decodes theimage data to generate pixel data for the image. The type of decodingused will depend on the format in which the image is encoded. In someembodiments, the system may include multiple decoders and will choosebetween the different decoders based on the format of the receivedencoded video.

The scheduling engine instructs the disk reader 1020 and the decoder1025 to perform their operations based on instructions received from theuser interface (indicating which media files are being imported andwhich operations should be applied to the media files). In addition, aswill be described below in Section II, the scheduling engine receivesfeedback from the image destinations 1040-1065 indicating the speed atwhich the images should be sent to the destinations.

The image destinations 1040-1065 include a high-resolution transcoder1040, a proxy transcoder 1045, a shake detector and corrector 1050, aperson detector 1055, a color balancer 1060, and audio operations 1065.These destinations receive images either directly from the decoder 1025or from intermediate image processing operations that are not shown inthis figure, but are described in detail below. The audio operations1065 do not receive or use image pixel data, but in some embodimentsreceive decoded audio at the same rate as the other destinations receiveimages. For instance if the video has a frame rate of 24 fps, someembodiments receive 1/24^(th) of a second of audio per decoded image. Ifthe audio is sampled at 48 kHz (48,000 samples per second), then theaudio operations would receive 2000 samples to correspond to one image.

The high-resolution transcoder 1040 generates a high-resolution encodedimage for each image received and stores these images in ahigh-resolution transcode file 1070. The proxy transcoder 1045 generatesa lower resolution encoded image for each image received and storesthese images in a proxy transcode file 1075.

The shake detector and corrector 1050 of some embodiments identifiesportion of the video in a media file in which the camera appears to beshaking, and tags the media file with a term such as “shake”. Users canthen search in the clip browser for clips with the “shake” tag andperform shake correction on these clips. Other embodiments automaticallyperform the shake correction when the shake is detected. In addition,some embodiments store an image stabilization file, or shake data file1080, for each media clip analyzed.

The person detector 1055 identifies people in the images of a media fileand saves the person identification information in a person detectionfile, or find people data file 1085, for each media file analyzed. Theperson detection operation of some embodiments identifies faces using aface detection algorithm (e.g., an algorithm that searches forparticular groups of pixels that are identified as faces, andextrapolates the rest of a person from the faces). Other embodiments usedifferent person detection algorithms.

The color balancer 1060 automatically balances the color of each imagein a media file and saves the color balancing information in a colorbalance data file 1090 for each media file analyzed. The color balancingoperation of some embodiments adjust the colors of an image to give theimage a more realistic appearance (e.g., reducing tint due to indoorlighting). Different embodiments use different color balancingalgorithms.

The audio operations 1065 may include analysis for audio problems,separation of mono audio channels and identification of stereo pairs,and removal of latent audio channels (i.e., channels of audio that areencoded but do not include any actual recorded audio). The output ofthese audio operations may be stored in one or more audio data files1095, stored as metadata of the media file, or may be used to directlymodify audio data in the media file.

As shown, the various media files 1070-1075 and the analysis data files1080-1095 are stored in the media storage 1015. In some embodiments, aswill be described in subsection D, these files are all stored in anorganized fashion in the file storage of the application.

As mentioned, the media-editing application performs the variousdifferent operations 1040-1065 in parallel in some embodiments. To dothis, some embodiments perform the operations as multiple concurrentlyprocessed threads for each image in a media file (i.e., a thread forencoding an image at high-resolution, a thread for performing shakedetection, a thread for balancing color, etc.). In addition, through thescheduling engine 1030, duplicative operations are removed. Rather thanhaving a separate disk read and decode for each of operations 1040-1065,the scheduling engine 1030 ensures that each image in a video is readonly once and decoded only once.

C. Editing a Clip on a Camera

As described in the above section, when a user imports a media file froma camera (or other external device), some embodiments create an assetdata structure for the media file that initially references the mediafile on the camera, and modify this reference once the media-editingapplication has copied the media file from the camera to a storagelocation associated with the application, often located on the boot diskof the device on which the application operates. The application alsocreates a clip data structure that refers to the asset (the details ofthese data structures and the references are described in subsection E).Because these data structures are created when the import processbegins, the media clip may be used for editing right away, even beforethe media files are copied (which could be a significant length of time,depending on the file size and the speed of the connection between thecamera and the computer). For instance, the user can add a clip to thetimeline and then trim the clip in the timeline without the underlyingmedia file having yet been copied to the application file storage.

FIG. 11 conceptually illustrates a state diagram 1100 of a media-editingapplication of some embodiments. One of ordinary skill will recognizethat the state diagram does not describe all states of the media-editingapplication, but instead specifically pertains to the import of a mediafile and the editing of that media file. As shown, the media-editingapplication is in a wait state 1105 before and after the import of themedia file. The media-editing application may be performing other tasks,including import- or editing-related tasks, at this time. In addition,at many of the other stages, the application could be performing a widevariety of tasks. In fact, in some embodiments, many of the importoperations (transcoding, analysis, etc.) are performed as backgroundtasks that the application pauses when performing other tasks (e.g.,editing).

When the media-editing application receives a command to import anexternal file, the application transitions to state 1110 as the importprocess starts. At state 1110, the application creates an asset and aclip that reference the external file and display the clip in thebrowser. As described above, the asset references the media file and theclip references the asset in some embodiments. An example of clips shownin the browser is illustrated in FIG. 3. At this state, the assetreferences the file on the camera (the external file).

The application then transitions to state 1115 to import the media file.During this state, the application copies the media file from the camerato the file storage associated with the application on a drive chosen bythe user. In some embodiments, this may be a time-intensive process,depending on the size of the file (and whether additional files arebeing imported at the same time) as well as the speed of the connectionbetween the camera and the computer.

If a user edits the clip associated with the media file while in theimport state, the application transitions to state 1120 to modify theproject data as required by the edit and display the edit in the GUI ofthe media-editing application. This edit might involve adding the clipto the timeline so that the clip is part of a user-created compositepresentation (also referred to as a project). The user could also editthe clip in the timeline (e.g., by trimming the clip, moving the clip,etc.), could open the clip in the timeline to directly edit the clipwithout adding the clip to a project, or perform other edits. Themedia-editing application modifies the appropriate data to record theedit in project data. For instance, if the clip is added to apresentation, the data associated with the presentation is modified toinclude a reference to the clip and information indicating where in thepresentation the clip is located.

If, after performing the edit, the file is still importing, themedia-editing application returns to state 1115. Once the file copyoperation is completed, the application transitions to state 1125 tomodify the asset data structure so that, instead of referencing the clipon the camera, the data structure refers to the newly created file inthe application folder. At this point, the media-editing applicationtransitions to state 1130 and begins performing any required transcodingand analysis on the imported file. The efficient parallel processingutilized by some embodiments to perform these operations is described inthe above section.

The transcoding and analysis may be a time-intensive process as well,depending on the size of the media file (i.e., how many images have tobe analyzed and how large the images are) and the processingcapabilities of the device performing the operations (e.g., theprocessing speed and number of processors).

While the application is at state 1130, analyzing the media file, themedia clip representing the file may be edited, in the same manner aswhen the application is at state 1115. That is, the user can add theclip to a project in the timeline, modify the clip in the timeline, editthe clip directly, etc. As before, when the application receives anedit, the application transitions to state 1120 to modify the projectdata as required by the edit and display the edit in the GUI of themedia-editing application. In some embodiments, the analysis andtranscoding tasks are performed in the background, and paused while theuser interacts with the application, then resumed after the edit iscomplete. This enables the device running the application to devote itsprocessing power to the user interactions rather than the analysis, andthen go back to the analysis when the processing power is not needed. Ifthe analysis is not complete when the edit is finished, themedia-editing application transitions back to state 1130 to continueperforming the operations.

Once the analysis and transcoding is complete, the media-editingapplication transitions back to 1105 to continue waiting. As shown,edits may be received from this state as well, in which case theapplication transitions to state 1120 to perform the edit, then returnsto 1105. As mentioned above, while in the wait state 1105, themedia-editing application may be importing additional files, analyzingthose files, and receiving edits to those clips, other clips, etc.

D. File Folder Structure of the Media-Editing Application

In some embodiments, importing a media file entails copying the mediafile to a particular storage as well as generating transcoded versionsof the media file and analysis data. The media-editing application ofsome embodiments stores the set of related files for each media fileimported into the application in an organized fashion in the file folder(i.e., directory) structure of one or more storage devices. The storagedevices may be physical devices such as an internal or external harddrive, or virtual devices such as a hard drive partition.

The following FIGS. 12-19 illustrate one example folder structure, asshown through a file navigation GUI 1200. One of ordinary skill willunderstand that this is simply one example of a folder structuregenerated by a media-editing application of some embodiments, and thatother embodiments may generate different folder structures to servesimilar purposes. As shown in FIG. 12, the GUI 1200 includes a list ofdevices and places at the left side. The devices currently accessibleinclude a hard drive and a USB drive. In this case, the hard drive isthe boot disk for the device on which the application operates, and isthe drive on which the file folders shown in file navigation GUI 1200are stored.

As shown, the highest level of file folders shown, in column 1205,includes a “Movies” folder and a “Music” folder. In some embodiments,when stored on a boot disk of the device on which the media-editingapplication operates, these folders are located in the file storageassociated with a particular user that is logged into the device. Thatis, some embodiments create a folder for each user of the device that isaccessible by that user. The folder for a particular user may include a“Movies” and “Music” folder as shown in these figures.

The “Movies” folder is currently selected. The “Movies” folder includesthree folders (shown in Column 1210): a “Final Cut Events” folder,“Final Cut Projects” folder, and “Final Cut Archives” folder. Whenstored on a non-boot disk (which may not include a “Movies” folder, someembodiments store the events, projects, and archives folders at the rootof the drive. In some embodiments, the projects folder stores data aboutprojects (e.g., composite presentations) created by a user with themedia-editing application. The archives folder stores camera archives insome embodiments, which are described below in subsection F of thissection.

The events folder, which is currently selected, includes a folder foreach event that the user (or users) has created (shown in column 1215).As described above, an event in some embodiments is a collection ofmedia assets. The assets may be grouped into events based on when themedia files are imported (i.e., clips imported together grouped into thesame event) as well as other criteria such as user decisions to createan event and place clips in the event. The two events created at thispoint are “Wedding” and “Event 4”. In many editing situations (e.g., thecreation of a feature film), a user will have created dozens, or evenhundreds, of events, each of which receives its own folder.

In the situation illustrated in FIGS. 12-19, the “Event 4” folder isselected in column 1215. The selected event folder includes foursub-folders, shown in column 1220 of the GUI 1200. These folders are“Original Media”, “Transcoded Media”, “Render Files”, and “AnalysisFiles”. In addition, some embodiments include a data file in the folderfor each event that describes the event. This may be a CoreData (SQLite)database file, an eXtensible Markup Language (XML) file, or other fileformat that is readable by the media-editing application to parse thedata structures (e.g., objects) that define the event and its assets. Insome embodiments, the original media folder stores copies of theoriginal imported files for an event, in their original format. Thisfolder is currently selected in FIG. 12, and includes three “.mov” files(i.e., QuickTime files), shown in column 1225. These are originalrecorded versions of movies that the media-editing application importedinto the “Event 4” event.

In FIG. 13, the transcoded media folder is selected in column 1220. Inthis case, the user has opted to have the application generate bothhigh-resolution (optimized) and low-resolution (proxy) versions of themedia files in the event, and thus column 1225 includes an “OptimizedMedia” and a “Proxy Media” folder. Some embodiments only create a folderfor a particular type of file when at least one such file is beinggenerated. That is, if there is no proxy media for a particular event,then the application does not create a proxy folder for that event (andif there is also no optimized media, the transcoded media folder is notcreated). The optimized media folder is selected, and thus three “.mov”files stored in this folder are displayed in column 1305. In someembodiments, the transcoded files have the same file name as theoriginal media files, as in this case. This allows an asset to referenceall of the files with this particular name, differentiating betweendifferent files based on the folder in which the file is located. FIG.13 illustrates the three high-resolution transcoded files thatcorrespond to the original media files shown in FIG. 12. In FIG. 14, theproxy media folder is selected in column 1225. As such, the figureillustrates the three low-resolution transcoded files that correspond tothe original media files shown in FIG. 12. As with the high-resolutiontranscoded files, these files have the same file names as the originalmedia.

In FIG. 15, the user has selected the render files folder in column1220. In some embodiments, the media-editing application uses such afolder to store data used for displaying the media clips in the mediabrowser or timeline of the application GUI. As shown, the render filesthat have currently been generated for “Event 4” include a “Thumbnails”folder and a “Peaks” folder (shown in column 1225). The thumbnailsfolder includes information for displaying the thumbnails in therepresentation of the media clip, while the peaks folder includesinformation for displaying the audio waveforms shown below thethumbnails in the clip representations.

Unlike the transcode and analysis files, the render files folders do notinherit the file name of the original media files in some embodiments.Instead, a hash (e.g., MD5 hash) of various properties of the file isused to generate the folder names shown in column 1305, which arehexadecimal numbers. FIG. 16 shows the peaks folder selected in column1225. Three different folders with three different hexadecimal names arenow displayed in column 1305 of the file navigation GUI 1200. Someembodiments use different properties to generate the hash names for thefolders for peaks as for thumbnails, so the folder names are differentin FIG. 16 as compared to FIG. 15. The properties that are used togenerate the hexadecimal folder names are various parameters about theunderlying media. Some embodiments include all properties that affectthe resultant render file (e.g., the thumbnail, waveform, etc.) and noproperties that do not affect the resultant file, with the goal that iftwo render files are exactly the same then their file name should beexactly the same.

In FIG. 17, the user has selected the analysis files folder in column1220. This causes any folders with analysis files to be displayed incolumn 1225 of the file navigation GUI 1200. In this case, the user hasselected to balance color, find people, and detect shake in the mediafiles of “Event 4”. In FIG. 17, the color adjustment folder is selectedin column 1225. In FIG. 18, the find people folder is selected in column1225, and in FIG. 19, the detect shake folder is selected in column1225. As these figures show, the files in each of these folders (colorbalance files, person detection files, and shake detection files,respectively) have the same file names as the original media, but withdifferent file names. In some embodiments, each analysis file has itsown file type, and stores the respective data in a format readable bythe media-editing application.

One of ordinary skill will recognize that the file folder names, filetypes, and folder structure are only one example of a set of foldersthat could be created by the media-editing application of someembodiments. Other embodiments might use different file names, differentfolder names, or a different folder organization (e.g., having thefolders for optimized and proxy media at the same level as the originalmedia folder).

E. Data Structures of Media-Editing Application

As indicated above, the media-editing application of some embodimentscreates an asset data structure (e.g., an asset object) for eachimported media file imported by the application, and also creates a clipdata structure (e.g., a clip object) for each asset that refers to theasset. When multiple related media files are imported (e.g., a videofile and several audio files), some embodiments create an asset for eachof these files and then a single clip that refers to the collection ofrelated assets. The following sub-section will describe these datastructures in further detail, as well as additional data structures usedby the media-editing application.

FIG. 20 conceptually illustrates a process 2000 of some embodiments forcreating an asset data structure and a clip data structure referencingthat asset. In some embodiments, process 2000 is performed as part ofthe import process of the media-editing application. The process 2000will be described in part by reference to FIG. 21. FIG. 21 conceptuallyillustrates an asset data structure 2100 for a video asset, as well asan event data structure 2105 for an event that contains the video asset.

As shown, the process begins by receiving (at 2005) a media file toimport. The media file may be an audio file, a video file, or other typeof media file. In the example shown in FIG. 21, the media file is avideo file with audio channels (e.g., a “.mov” file).

Next, the process creates (at 2010) an asset data structure for themedia file. At this point in the process, the asset data structure is anempty structure. Some embodiments define the data structure in aCoreData (SQLite) database file, an XML file (e.g., an XML file for anevent), etc. As mentioned, FIG. 21 illustrates an asset data structure2100 for the media asset. The asset data structure 2100 is fullypopulated, and this data will be described further below.

In some embodiments, the asset data structure is created within an eventdata structure. If the event data structure does not yet exist, then themedia-editing application also creates this data structure to containthe asset. As shown in FIG. 21, the asset data structure 2100 is oneasset within the event data structure 2105. The event data structure2105 includes an event ID 2110, the list of assets, and a list of clips.The event data structure may include additional fields in someembodiments, such as the event name, event date (which may be derivedfrom asset information), etc. The event data structure 2105 may be aCoreData (SQLite) database file that includes the assets and clips asobjects defined with the file, an XML file that includes the assets andclips as objects defined with the file, etc.

The process next retrieves (at 2015) metadata from the imported file,and then stores (at 2020) this metadata in the asset structure. Themetadata is information about the source file and its stored media insome embodiments. In some embodiments, this metadata is used to generatethe asset ID, described below. The asset data structure 2100, as shown,includes source file metadata 2115. As shown, the source file metadataincludes the file type (e.g., audio, video, movie, still image, etc.),the file format (e.g., “.mov”, “.avi”, etc.), the source device (i.e.,the device that created the media, such as the particular type of cameraon which a movie file was captured), the file creation date (e.g., thedate a video was captured, rather than the date of import), a UUID (aunique identifier generated by a media creation device such as acamera), a set of video properties 2120, a set of audio properties 2125,and additional metadata. Different types (or manufacturers) of camerascreate different UUIDs differently. These may be hashes of various datain some embodiments, such as a camera ID, record time (e.g., the time auser of the camera started recording, the duration of the video), etc.,so long as all UUIDs are unique.

The video properties 2120 of some embodiments include such properties asa sample rate, a frame rate (i.e., the number of video images the videofile contains per second, often 24, 25, or 30), the dimensions of theimage (i.e., the number of pixels horizontally and number of rows ofpixels), the pixel aspect ratio (i.e., the shape of the pixels, whichmay be square (HD video) or rectangular (e.g., NTSC video has a ratio of10:11)), the pixel transform (described in detail below in Section V),and the colorspace in which pixel values of the image are defined (e.g.,ITU-R BT.709 for HD, ITU-R BT.601 for SD, etc.). The audio properties2125 of some embodiments include a sample rate (i.e., the number ofaudio samples per second, often 48 kHz), the number of audio tracksstored in the underlying media file, and the number of audio channelsstored in the underlying media file. In some embodiments, the asset mayadditionally store override data that modifies one or more of the videoor audio properties. For instance, a user might enter that a media fileis actually 1080p, even though the file's metadata, stored in the asset,indicates that the video is 1080i. When presented to the user, or usedwithin the application, the override will be used and the media filewill be treated as 1080p.

Returning to FIG. 20, the process 2000 then creates (at 2025) an assetID and stores the asset ID in the asset structure. The asset ID, in someembodiments, is a function of various properties of the underlying mediafile. For instance, some embodiments generate the asset ID as a hash ofproperties such as a file identifier, video properties, audioproperties, and media range. The creation of the asset ID will bedescribed in further detail by reference to FIG. 22. As shown in FIG.21, the asset ID 2110 is stored in the video asset 2100.

With the asset created, the process 2000 then begins populating theasset with references to various data. The process stores (at 2030) areference to the original media file in the asset structure. Asdescribed above by reference to FIG. 11, this reference initially refersto the media file on the device from which the application is importingthe file (e.g., the camera), and then once the file is copied to theapplication's folder structure, the reference is modified to refer tothe copied media file.

Next, the process 2000 creates (at 2035) a clip data structurecontaining a reference to the asset. In some embodiments, a clip iscreated for each asset. As will be described below, clip data structures(e.g., clip objects) can also contain other clips, and some embodimentsuse the same data structure for single asset clips, compound clipscontaining multiple assets and/or nested clips, and project sequences.The clip data structure, like the asset, is contained in the event datastructure in some embodiments. Some embodiments create a series ofnested clip objects for an imported clip, as described in further detailbelow. The lowest clip object in the nested hierarchy references theasset.

Next, the process determines (at 2040) whether any transcoded versionsof the media are generated by the media-editing application. Asdescribed in subsections A and B above, some embodiments generate one ormore transcoded versions of imported media files in formats that arebetter suited for editing. This may be an automatic process based on theimported file properties, or based on user selection of whether totranscode the media. When one or more transcoded versions of the mediaare created, the process stores (at 2045) references to any suchtranscoded versions of the media file in the asset data structure.

The process also determines (at 2050) whether any analysis data isgenerated for the media by the media-editing application. As describedabove, some embodiments generate data about the video and/or audio dataof a media file. This data may be generated automatically or based onuser selection of particular analysis operations. When one or moreanalysis data files are created, the process stores (at 2055) referencesto any such analysis data files in the asset data structures. Theprocess 2000 then ends.

The media asset 2100 of FIG. 21 includes references to three versions ofthe underlying media file: a copy of the original media file 2130, ahigh-resolution transcoded media file 2135 (e.g., a ProRes 422 file),and a low-resolution transcoded media file 2140 (e.g., a ProRes Proxyfile). In addition, the media asset includes references to a persondetection file 2145, a color correction data file 2150, and a shakecorrection data file 2155. These data files are described in furtherdetail in the subsections above. In some embodiments, the referencesstored in the asset data structures are pointers to the locations of thevideo on a physical storage device (e.g., the boot disk of the device onwhich the media-editing application operates). In the case of mediaasset 2100, the underlying file stores both audio and video. In somemedia formats, different files are used to store video and audio for asingle shot (and there may be multiple audio files recorded by differentaudio recorders in some cases). In this case, some embodiments createseparate assets for each file. In some embodiments, each media file getsits own asset data structure.

As mentioned in the discussion of FIG. 21, the asset ID for a particularasset may be generated using various properties of the asset'sunderlying media file. FIG. 22 conceptually illustrates a process 2200of some embodiments for generating the asset ID and storing the ID inthe data structure. In some embodiments, process 2200 is performed atoperation 2025 of process 2000.

As shown, the process 2200 begins (at 2205) by receiving a media file(e.g., a video file, audio file, movie file, etc.). The process thenidentifies (at 2210) the media file ID, video properties, audioproperties, and media range of the media file. As shown in FIG. 21,these may be stored as metadata of the source media file. The media fileID, in some embodiments, is a UUID generated by a camera that shot themedia file, as described above. In some cases, the file may not have aUUID (e.g., if the device that captured the file does not generateUUIDs), and some embodiments will instead use the file name. The videoproperties used in some embodiments are the dimensions, colorspace,field dominance, sample duration, frame duration, pixel transform, andpixel aspect ratio, though different video properties may be used indifferent embodiments. The sample duration may be different from frameduration if, for example, the video is field rendered, in which case theframe duration is twice the sample duration. The frame duration, in someembodiments, is the inverse of the frame rate (e.g., if the frame rateis 30 fps, then the frame duration is 1/30 of a second). The audioproperties used in some embodiments are the number of tracks, number ofchannels, and sample rate (i.e., the same as shown in audio properties2125). Some embodiments include additional properties, such as the filecreation date (i.e., the date and/or time at which the media wascaptured (e.g., filmed, photographed, recorded, etc.)).

The media range indicates the range of the original media filereferenced by the particular asset. Some embodiments use timecode valuesof the media file to define the media range. Thus, if a file is splitapart (e.g., a user might take a thirty minute video and split it into atwelve minute video, a seven minute video, and an eleven minute video,as well as retain the original), the different timecodes willdifferentiate the assets. The media range can also be used if one of theassets goes missing, as an asset with identical properties and a rangeincluding the media range of the missing assets can be used to restorethe missing asset.

The process then generates (at 2215) a hash of the identified propertiesof the media file. Different embodiments use different hash algorithms(e.g., MD5, etc.). The process then stores (at 2220) this generated hashin the asset structure as the asset ID. While the process 2200 describesone method of computing an asset ID, one of ordinary skill willrecognize that asset IDs can be computed using many different propertiesand many different computation algorithms.

As mentioned by reference to FIG. 20, some embodiments use a clipstructure that references one or more assets when importing a mediafile. FIG. 23 illustrates a component clip data structure 2300 of someembodiments that references an asset. In some embodiments, the componentclip 2300 is the lowest level of a set of nested clip objects, which areall members of the same class. The details of clip objects of someembodiments will be described below by reference to FIG. 24.

The component clip 2300 includes a clip ID, clip attributes (describedin more detail below), and an asset reference 2305. The asset reference2305 of some embodiments stores an event ID and an asset ID, anduniquely identifies a particular asset data structure, as indicated bythe dashed arrow referring to an asset. The arrow is shown as dashedbecause the asset reference is not a direct reference to the asset, butrather is used to locate the asset when needed. When the media-editingapplication of some embodiments needs to identify a particular asset,the application uses the event ID to locate the event that contains theasset, and then the asset ID to locate the particular desired asset.

FIG. 24 conceptually illustrates a nested sequence of clip objectscreated by the media-editing application of some embodiments for animported media file. In some embodiments, each of the clip objects shownin this figure is a member of the same class, though the object may beof different sub-classes. The media file whose clip structure isillustrated in FIG. 24 is a movie file that stores both audio and videoinformation.

The figure illustrates a sequence 2405, a collection 2410, and twocomponents 2415 and 2420. As mentioned, these three types of objects areall subclasses of clip objects (or anchored objects) in someembodiments. Some embodiments create a sequence within an event objectfor each imported media clip. The sequence 2405 stores a sequence ID, aset of sequence attributes, and the collection object 2410. The sequenceID is a unique identifier for the sequence object. The sequenceattributes, in some embodiments, include video properties for thesequence, such as the resolution, frame rate, etc. The attributes may beset by a user in some embodiments, or set automatically based on theunderlying media.

The collection object 2410 is an ordered array of clip objects. In thecase of a clip imported into an event, as is the case with object 2410,the collection stores one or more component clips in the array. Often,the collection only stores the video component clip in the array, asshown here; any additional components (generally one or more audiocomponents) are then anchored to that video component. In addition, thecollection object 2410 stores a collection ID, a total range, and atrimmed range. The collection ID is a unique identifier for thecollection object. The total range of a clip object indicates themaximum range for the object based on the objects it contains, while thetrimmed range indicates the actual range of the object in its parentobject according to user edits. In some embodiments, the collectionobject stores a value for the total range because the total range is avariable assigned to all types of clip objects, but this range is notactually used by the application. Instead, the application dynamicallycalculates the total range based on the objects contained by thecollection (as opposed to updating the range value every time a clip isadded to the collection). Some embodiments, on the other hand, do updatethe total range in the collection object. These ranges will be describedin further detail below by reference to FIG. 25. The array of thecollection object includes two media components 2415 and 2420.Collection objects, in some embodiments, can include component clipobjects as well additional collections.

In the above paragraph and elsewhere in this section, a first object(e.g., the collection object 2410) is described as containing a secondobject (e.g., media component 2415 in the collection object's array). Insome embodiments, a first object contains a second object by storing areference to the object (e.g., a pointer). This reference is a strongpointer in some embodiments.

The media components shown include a video component 2415 and an audiocomponent 2420. These are the same data structures as the component clip2300, in some embodiments, and thus store the clip attributes and theasset reference shown in that figure. Each of the components stores acomponent ID (i.e., the clip ID of FIG. 23), a source media range (i.e.,total range) and a trimmed range. For a component clip that refers to amedia asset, the total range is the duration of the source media. Thetrimmed range is the range selected by a user through various user edits(e.g., trim edits) and indicates both the start time within the totalrange and the duration, in some embodiments. The trimmed range isgenerally a subset of the total range (i.e., does include time outsidethe total range). However, in some embodiments, the application may usea range extender to extend the trimmed range past the total range (e.g.,when needed for part of a transition, or if aligned audio runs slightlylonger than video). Some embodiments will generate video images using,e.g., the first and last images of the video file, to fill in the neededextra range. When a clip is initially imported into the application, thetotal range and trimmed range will generally be equal as the user willnot have edited the clip at all yet.

The video component 2415 includes an anchored item set that contains theaudio component 2420. As described above by reference to the timeline315 in the user interface 300 of FIG. 3, clips can be anchored to otherclips in some embodiments. When a particular clip is moved in atimeline, any clips anchored to the particular clip are moved along withit. Each clip can have numerous clips anchored to it, and can beanchored to a single clip. In the case of a media clip with audio andvideo components, some embodiments anchor the audio component to thevideo component. Thus the video component object 2415 contains the audiocomponent in its set of anchored items (and could include numerous suchitems if there were additional audio components), while the audiocomponent object 2420 includes a parent item reference to the videocomponent to which it is anchored. In addition, the child (anchored)object stores an anchor offset that indicates two values. The firstvalue is the position in the parent object to which the child object isanchored, and the second value is the offset within the child object ofthe anchor. In the case of an imported media file, the audio and videocomponents will start at the same time, and thus both anchor offsetvalues are zero. However, this can be modified if, for example, there isa slight offset in the recordings of the two components and the user hasto adjust the audio relative to the video.

FIG. 25 conceptually illustrates the objects 2405-2420 nested in aconceptual timeline. The figure shows video and audio components 2415and 2420 inside the collection 2410, which is nested inside the sequence2405. The audio component 2420 is anchored to the video component 2415;specifically, as shown by the thick arrow 2505, the start of the audiocomponent is anchored to the start of the video component.

The figure also includes a dashed box 2510 that illustrates that a userhas trimmed the clips so that portions at the beginning and end of theclip are not part of the sequence were it to be rendered. Thus, thetotal media range of the components is the full length of the media towhich they refer, whereas the trimmed range is a subset of this rangebased on the user edits. In some embodiments, all clip objects store atotal range and trimmed range. The collection 2410, in this case, willhave the same total range and trimmed range as the components. However,if the components were offset, or if the collection included additionalobjects, it would have larger trimmed and total ranges. For sequenceobjects, the total range and trimmed ranges are always equal in someembodiments. In the illustrated case, the sequence 2405 has a rangeequal to the trimmed range of the collection 2410. As the user edits theobjects in the sequence, both the trimmed and total range of thesequence change.

FIG. 26 illustrates a timeline 2600 with a project title “New Project”that includes four clips 2605-2620. The clips 2605-2615 are in theprimary compositing lane of the project's sequence, while the clip 2620is anchored to clip 2610 at approximately 26 seconds into clip 2610. Theclip 2610 is a compound clip that itself includes two clips.

FIG. 27 conceptually illustrates a subset of the data structures for thesequence illustrated in FIG. 26. In some embodiments, the datastructures of FIG. 27 are all contained within a project data structurethat contains a single sequence. In some embodiments, the project datastructure for a project in the timeline is a sub-class of a class thatalso includes event data structures. Unlike the project data structures,the event data structures can contain multiple sequences, and in factcontain a sequence (such as sequence 2505) for each clip in the event.

FIG. 27 illustrates a sequence 2700 that includes a primary collectiondata structure 2703, which itself is an array of three collections2705-2715 that correspond to the clips 2605-2615. In addition, thefourth clip 2620 is stored as a data structure within the collection2710. For simplicity, the component objects are not shown in thisfigure. The sequence 2700 includes a sequence ID, sequence attributes,and the primary collection 2703. The sequence attributes for a projectin the timeline are set by a user when creating the project, in someembodiments.

The primary collection 2703 includes the collection ID, total andtrimmed range, and the array of media clips. In some embodiments, thearray is ordered based on the location in the timeline and only includesmedia clips in the primary lane of the collection. The applicationassumes that there is no gap between these items, and thus no timingdata is needed between the items. As shown, each of these clips isrepresented as a collection. When a clip stored in an event (e.g., theclip shown in FIG. 24) is added to a project in a timeline, someembodiments remove the sequence container data structure (e.g.,structure 2405) and copy the rest of the structure (i.e., the collectionand its components) into the data structure for the object in thetimeline.

Clips 2705, 2715, and 2720 are individual clips that have been added tothe timeline from the clip browser, and thus do not themselves includecollections. Similar to the collection 2410, these objects include anID, total and trimmed ranges, and an array of media components (e.g., avideo component and one or more audio components).

The clip 2710 is a compound clip and therefore includes multiple clipsin addition to the collection ID and ranges. Specifically, the clip 2710includes two media clips 2725 and 2730. Within the collection, the clipsare both in the primary lane of the collection, and thus one follows thenext. These clip objects are not shown in this figure, but each of theclips is similar to clip 2705 in that the clips include an array ofmedia components. In addition, the clip object 2710 includes a set ofanchored items (in this case only the one item, clip 2720). Someembodiments include a set of anchored items for each collection, whichare empty for the other objects shown in this figure. The anchor offsetstored in clip 2720 indicates that it is anchored 26 seconds into clip2, and that the anchor is at the start of clip 2720. These times referto the trimmed ranges of the clips in some embodiments.

FIG. 28 conceptually illustrates the objects 2700-2730 nested in aconceptual timeline. As shown, collection objects 2725 and 2730 arenested inside the collection 2710, which is nested inside the primarycollection object 2703 along with the collection objects 2705, 2715, and2720. The collection object 2703 is itself nested inside a sequenceobject.

The figure illustrates the anchoring relationships between the variousclips as well as the durations (ranges) of the clips. As with the clipobjects shown in FIG. 25, each of the lowest level collections 2705,2715, 2725, and 2730 each have an audio component anchored to a videocomponent. While not shown, collection 2720 could also have the samevideo/audio setup, or could be just a video component (or just an audiocomponent). While each of the objects shown has a single audiocomponent, one of ordinary skill will recognize that some embodimentswill have multiple audio components (e.g., if a camera records severalaudio tracks as separate files and imports the files with a video fileas part of a single clip).

The figure also illustrates the anchoring of clip 2720 to clip 2710. Insome cases, multiple clips will be anchored to the same primary laneclip, and the multiple anchored clips may overlap in time. In this case,multiple secondary lanes may be used. Some embodiments assign lanenumbers to each clip object that indicates the clip object's lane withina collection.

All of the primary lane objects are assigned a lane number of zero insome embodiments, with lanes above the primary lane getting increasingnumbers and lanes below the primary lane getting decreasing (negative)numbers. For instance, a separate audio clip might be anchored to a clipin the primary lane and displayed below the primary lane. In this case,within the primary collection 2703, the anchored clip 2720 has a lanenumber of 1. The lane numbers indicate compositing order for video insome embodiments. Whereas two audio files can be combined fairly easily(mixed), two video files cannot be displayed at the same time. Thus,some embodiments composite higher lane number clips on top of lower lanenumber clips. If no compositing effect is defined between two clips atthe same time, then the clip in the higher lane will be displayed.However, various compositing modes and effects may be used to combinethe pictures (e.g., compositing modes such as subtract, darken,multiply, etc. that combine pixel information of two images, as well aseffects such as scaling the top image to get a picture-in-picture,applying a color mask to the top image, etc.).

The items in a lower-level nested collection will also have lane numbersthat refer to their lane order within that collection. For example, thecollection object 2710 has two clips 2725 and 2730, that each have alane number of zero. However, this collection object could have anchoredclips in multiple lanes. For the purpose of compositing at time ofrendering, the items within the collection 2710 would be compositedinitially according to the ordering within the collection, then theoutput of that would be composited within the primary collectionaccording to the ordering of the primary collection. Similarly, for eachof the lowest-level collections (e.g., collection 2705), the videocomponents are all lane zero and the audio components are lane −1.

FIG. 28 also illustrates the ranges (e.g., durations) of the variousclip objects. For the lowest level collections and their components(e.g., collections 2705, 2715, 2725, 2730, and 2720), the trimmed rangeand the total range are determined in a manner similar to that shown inFIG. 25 for the collection object 2410. In this case, collections 2715and 2755 are not trimmed at all, whereas collection 2705 is trimmed onboth sides and the start of collection 2730 is trimmed.

For collection 2710, the total range is the sum of the trimmed ranges ofits primary lane clips, which in this case are collections 2725 and2730. Thus, the variable Total Range 2=Trimmed Range A+Trimmed Range B.In this case, the collection 2710 is not separately trimmed, such thatits trimmed range equals its total range. This means that, althoughthere is more media within clip 2730, while editing the primarycollection 2703 the media-editing application will not allow a user toincrease the duration of clip 2710 beyond that of Total Range 2.However, a user could open up the clip 2710 in the timeline and applytrim edits to either of clip 2725 and 2730. Modifications to the trimmedrange of these clips will affect the total range of the clip 2710. Inaddition, within the primary collection 2703, a user can modify thetrimmed range of clip 2710 to shorten the clip. Trimming from thebeginning would result in less of the media of collection 2725 beingused in the component presentation, while trimming from the end wouldresult in less of the media of collection 2730 being used in thecomposite presentation.

The above figures illustrated various aspects of different subclasses ofclip objects (e.g., sequences, collections, and components). One ofordinary skill will recognize that clip objects of some embodiments mayhave additional properties not shown in these figures. For instance,both collections and components may have an effect stack in someembodiments, which stores a stack of effects that are applied to themedia in the clip when the application renders the clip. The applicationapplies these affects to the media in an order designated by the effectsstack, which can be modified by the user during editing. The effects mayinclude audio effects that perform a transform on the audio or videoeffects that apply a function to the pixel values of the video images,in some embodiments. In fact, some embodiments store separate video andaudio effects stacks.

In addition, one of ordinary skill in the art will recognize that someembodiments may have additional different subclasses of clip objects.For instance, some embodiments store generators, transitions, auditionstacks, markers, and keywords as clip objects. A generator, in someembodiments, is an effect used in a composite presentation that createsits own video images rather than modifying existing images (e.g., cloudsand other computer-generated effects that may rely on random processes).Some embodiments also use generators as gap elements in collections inspecific circumstances. If, for example, a user were to select clipobjects 2705 and 2720 and create a compound clip from these objects, agap element would be inserted into the collection object for thecompound clip to take up the missing space of clip object 2710, whichthe user did not add to the collection. The clip object 2720 would thenbe anchored to this gap element. In some embodiments, these clips arenot actually generators, but are special clips that produce neitheraudio nor video but add duration to a collection. As the generatorscreate their own video images, they have a duration and this durationadds to the range of the collection containing the generator.

Transition objects, on the other hand, are used for transitions betweentwo other clip objects. These objects have a range of 0, and do not addto the range of the container clip object. A transition object is storedin the array of its containing collection with an index between theindices of the two items between which it transitions. The transitionobject has a head and a tail that indicate the start and end of thetransition between the clips.

Audition stack objects, or variants, store a list of possible clips fora particular index in a collection or for a particular anchor. That is,the audition stack object stores a set of clips, one of which isdesignated as active at any time. The properties of the stack objecttake on the properties of the active clip, such as the ranges, videoproperties (e.g., frame rate, resolution, etc.), audio properties, etc.Thus, when a user switches the active clip in the stack, some attributesof the stack may change. In addition, some of the objects in the stackmay be collections that themselves have nested clips, while others mightbe simpler clip objects. When an audition stack object is anchored toanother clip, some embodiments store the first portion of the anchoroffset in the audition object (i.e., the offset within the parent clip),but store different offsets within the child clip for the differentclips in the audition.

Marker objects store markers that a user adds to a specific timelocation in a collection. In some embodiments, marker objects have aduration of 1 frame, and store metadata indicating the type of marker(e.g., to do marker, analysis marker, etc.) and any notes about themarker that the user adds. Some embodiments anchor marker objects to aparticular clip object. When calculating the duration of a collection,marker objects are specifically excluded from this calculation in someembodiments.

Finally, keyword objects store keyword tags about a clip object. Unlikemarkers, keywords have a range, as some embodiments provide the user theability to tag a particular range of a clip rather than just associatingthe keyword with the entire clip. In some embodiments, a keyword objectcan store multiple keywords that have the same range. Some embodimentsanchor keyword objects to the tagged clip object at the start of therange within the tagged object. Like markers, some embodimentsspecifically exclude keyword objects from the duration calculation for acollection.

The above-described data structures (e.g., the clip objects, assetobjects, event objects, project objects, etc.) are used by someembodiments of the media-editing application for displaying informationin the GUI of the application as well as for rendering the compositepresentations. As alluded to above, in some cases the media-editingapplication will attempt to access a clip (e.g., to display the clip inthe media browser or timeline), but will be unable to resolve theunderlying asset. In this case, the application may report that theasset is missing and provide an option to find a replacement asset. FIG.29 conceptually illustrates a process 2900 of some embodiments forsearching for an asset.

As shown, the process 2900 begins by receiving (at 2905) a request toperform a function on a clip that requires access to the asset. The clipmay be a clip that includes multiple assets, or a component clipincluding only one asset. This function may simply be displaying arepresentation of the clip in the timeline (e.g., because a user hasrequested that a project including that clip be displayed in thetimeline for editing), or performing more complex editing operations onthe clip.

The process retrieves (at 2910) an event ID and asset ID from the assetreference in the clip. As shown in FIG. 23, the clip data structurestores an asset reference in some embodiments that includes both ofthese IDs. The process then determines (at 2915) whether an event can befound in the media-editing application database with the retrieved eventID. In some embodiments, the process searches an event database storedby the media-editing application for an event with the event IDretrieved from the asset reference. As shown in FIG. 21, each event hasa unique event ID. When no such event can be found, the process reports(at 2920) a missing event, and ends. The media-editing application maydisplay this information to the user. The display of such information isdescribed in further detail below in Section IV. In some cases, a usermight have deleted an event in order to delete the associated media andanalysis files, thereby saving disk space. In addition, the event mightbe stored on a physical storage device (e.g., an external hard drive)that is not connected to the device on which the application isoperating.

When an event is found with the event ID from the clip, the processdetermines (at 2925) whether an asset with the retrieved asset IDcurrently exists in the identified event. In some embodiments, theprocess searches within the event for an asset having the requestedasset ID. As shown in FIG. 21, each event includes a list (e.g., anarray) of the assets in the event stored by asset ID, and each assetstores its own asset ID as well.

When no such asset can be found, the process reports (at 2930) a missingasset, and ends. The media-editing application may display thisinformation to the user. The display of such information is described infurther detail below in Section IV. In some cases, a user might havedeleted various clips from an event through the media browser, thinkingthat the clips are not needed. As the notion of an asset, as opposed toa clip, is not shown to the user of the application in some embodiments,in some embodiments deleting the clips in the clip browser deletes theasset as well (whereas deleting a clip from a project in the timelinedoes not affect the underlying asset). Some embodiments provide twodifferent deletion functions—a user can either delete just a clip froman event but keep the asset, or delete the asset (and the underlyingmedia) with the clip.

When the asset is found, by matching both the event ID and the asset ID,the process performs (at 2935) the requested function on the clip, andends. This process illustrates two possible failure modes: a missingevent and a missing asset (which is reported to the user as a missingclip). In addition, some embodiments include other failure modes. Forinstance, a file may be missing, if a user requests proxy media but hasnever generated a proxy version of a particular file, or if a user hasmanually deleted files through the directory folder structure of thedevice on which the file was stored. In the latter case, the asset datastructure would remain, but would point to a nonexistent file.

When a clip has an unresolved asset, some embodiments provide for theability to identify a new clip with the same asset. This may be inresponse to a user request to find a replacement asset, or be performedautomatically by the media-editing application. FIG. 30 conceptuallyillustrates a process 3000 of some embodiments for resolving such amissing asset.

As shown, the process 3000 begins by receiving (at 3005) a clip with anunresolved asset (i.e., a missing asset). The missing asset may havebeen discovered through a process such as that shown in FIG. 29. Theprocess then identifies (at 3010) an identity for the asset thatexcludes the media range. This allows the application to find areplacement asset that references a media file created from the sameshot or recording as the missing asset, but might have a different mediarange.

Next, the process determines (at 3015) whether any assets are found withthe same identity as the missing asset. As stated, this would be anasset that references a media file created from the same shot orrecording as the missing asset. This might be another copy of the samefile, or a file split off from a larger file (e.g., half of a longrecording). Such a file would have the same video properties, audioproperties, and media file ID, but might have a different media range.When no such assets are found, the process will be unable to resolve themissing asset, and ends.

When the application finds one or more such assets, the processdetermines (at 3020) whether any of the assets include the media rangeof the missing asset. If the identified asset includes the entire rangeof a missing asset, then the asset is suitable for use by the clip withthe missing asset. On the other hand, if the clip previously referred toan asset with media not part of the identified asset, then modifying thereference to the new asset will not be useful. If none of the identifiedassets include the media range required by the clip, the process isunable to resolve the missing asset, and ends.

However, when one or more of the identified assets includes the mediarange needed, the process modifies (at 3025) the clip to refer to one ofthese identified assets, then ends. To modify the clip, the applicationmodifies the data structure of the clip to replace the asset referencefor the missing asset with the asset reference of the newly identifiedasset. This will often be both a new event ID and a new asset ID. Whenmultiple assets are found that include the media range needed by theclip, some embodiments select the first identified asset and use thatasset. Some embodiments allow the user to prioritize different eventsand select the highest-priority event with a qualifying asset. Otherembodiments use the asset with the longest media range, or the mediarange closest to that of the original asset.

FIG. 31 conceptually illustrates a state diagram 3100 for amedia-editing application of some embodiments. Specifically, statediagram 3100 refers to the creation and modification of clip data due tovarious user actions. As shown, when the application is not receivingany such actions, the application is in the wait state 3105. One ofordinary skill in the art will recognize that the application might beperforming many other actions while in the wait state with reference tothis figure (e.g., performing background tasks such as rendering,analysis, and transcoding).

When a user imports a file, the application transitions to 3110 tocreate a clip object in an event for the imported file. The event objectmay also need to be created, depending on whether the user is importingthe file to an existing event. As described above, in some embodimentscreating the clip object entails creating one or more assets within theevent that refer to the file (and any transcodes of the file), as wellas creating a sequence that contains a collection with the mediacomponents of the imported file, which refer to the asset or assets. Theapplication then returns to the wait state 3105.

When the user adds a clip to the timeline (e.g., by dragging the clipfrom the browser to the timeline), the application transitions to 3115and duplicates the clip object from the event to create a new clipobject that is part of the project currently edited in the timeline. Thenew clip object, in some embodiments, will have the sequence containerobject removed and will include the collection object and thecomponents. In some embodiments, the user may add only a portion of theclip from the event browser to the timeline, in which case the trimmedrange of the collection object and its components will be less thantheir total range. In addition, the application transitions to 3120 toadd information for the new clip object to the timeline clip objectattributes. That is, the collection (e.g., a primary collection of asequence) is modified to include the new clip object in its array. Ifthe clip is added to the middle of the timeline (in between otherclips), then some embodiments insert the new clip object to thecorresponding index in the array and move the later clips down to higherindices. The application then returns to the wait state 3105.

When the user duplicates a clip in the timeline (as opposed to adding aclip from the browser), the application transitions to 3125 to duplicatethe clip object from the clip in the timeline. In this case, there is nosequence object to strip off of the clip object, so the information cansimply be duplicated. In addition, the information about the new clip isadded to the timeline clip object at state 3130. In some embodiments,this may require modifying the indices in the array for the collectionobject represented in the timeline.

When the user edits a clip in the timeline (e.g., moves the clip), theapplication transitions to 3135 to modify the information for the editedclip object and the timeline clip object. For instance, when a clip ismoved in time, the indices of one or more clip objects will have to bemodified in the collection object represented in the timeline. When aclip is trimmed, the trimmed range of its clip object and componentswill have to be modified. When a clip is moved from a primary lane to ananchored position in a secondary lane of the timeline, the array of thecollection will be modified so that the moved clip object is at a laterindex. In addition, the application will modify the clip object toindicate the anchoring and modify the object to which it anchors for thesame reason as well. One of ordinary skill in the art will recognizethat other types of edits (e.g., moving a clip object from an anchoredposition to the primary lane) will have similar effects on the clip datastructures.

F. Camera Archives

As mentioned in subsection D, in describing the folder structure used bythe media-editing application of some embodiments, the application maystore camera archives. Some embodiments store a copy of all media fileson a camera (or other recording device) as an archive bundle, from whichthe files can be imported at a later time. The bundle, in someembodiments, is a set of files wrapped up in such a way that they appearas one item to a user. This prevents the user from easily modifying thebundle, either intentionally or accidentally, and thereby ensures thatthe original source files are still available at a later time.

FIG. 32 illustrates the creation of a camera archive in four stages3210-3240. Stage 3210 illustrates the clip library 305 and clip browser310, while stages 3220-3240 illustrate the import window 400. The GUIelements of these items have been described in detail above insubsection A. As with FIG. 3, in stage 3210 the user is selecting theimport initiation item 345, causing the display of the import window400.

Stage 3220 illustrates that the import window 400 is now displayed. Onthe left, the list of current camera archives is displayed. Currentlythe display lists three archives on an external hard drive (ExternalHD), with no archives on the boot disk hard drive (Macintosh HD). Theseare all archives created at one time or another of the contents of theVPC-GH4 camera, unless the user has misnamed the archives. As shown atstage 3220, the user is selecting the camera VPC-GH4.

The third stage 3230 illustrates that the user has selected cameraVPC-GH4, such that the application displays the media stored on thiscamera in the browser area 415 and preview area 425 of the import window400. At this stage, the user selects the “Create Archive” option 3205from the set of user selectable items 435.

The selection of the option 3205 brings up an archive creation dialogbox 3200 in stage 3240. The media-editing application displays thisdialog box over the import window in some embodiments, as shown. Thedialog box includes a field for the user to enter a name for the cameraarchive, as well as a drop-down menu for the user to select a drive ontowhich the archive will be stored. The application of some embodimentscreates a folder on each drive that stores any camera archives stored onthat drive, so that the archives are easily accessible by themedia-editing application in a designated location. In this example, theuser has typed “VPC-GH4 4” for the name of the camera archive, and isstoring the archive to the external drive. When the user selects the“OK” item, the application creates the archive as a bundle file andstores it with the name “VPC-GH4 4”.

FIG. 33 illustrates the import of a set of media files from a cameraarchive over four stages 3310-3340. As with FIG. 32, stage 3310illustrates the clip library 305 and clip browser 310, while stages3320-3340 illustrate the import window 400. Stage 3310, is the same asstage 3210, in which the user is selecting the import initiation item345, causing the display of the import window 400. Stage 3320 is thesame as stage 3220, except that the list of camera archives lists thenewly-created “VPC-GH4 4” archive in addition to the previous threecamera archives. In addition, the user is selecting this archive fromthe list at this stage.

At stage 3330, the user has selected camera archive “VPC-GH4 4”, andthus the application displays the media from the archive in the browserarea 415 and preview area 425 of the import window 400. The mediaappears as shown in stage 3230 of FIG. 32: that is, the display of themedia from a selected camera archive will be the same as the display ofthe same media from a camera, in some embodiments. As shown, the userselects the “Import All” selectable item 450 at this stage.

The fourth stage 3340 illustrates that the application displays theimport dialog box 455 as a result of the user selecting the selectableitem 450. The import dialog box 455 is described above by reference toFIG. 4, and allows the user to select from a number of operations toperform on the imported media files. These operations includetranscoding operations to create additional versions of the media files,analysis operations to generate data about the media files, etc. Inaddition, the user can either create a new event for the media or addthe media to an existing event. In this case, the user has selected tocreate a new event and save that event to the boot disk (Macintosh HD).In addition, the user has selected to create only a high-resolutiontranscode of the media, with no low-resolution transcode, and notperform any analysis. The result of the user selecting the import buttonis the addition of the newly created event “Event 4” to the eventlibrary, in a similar fashion to that shown at stage 440 of FIG. 4.

Subsection D above described the folder structure of some embodiments,and mentioned that the media-editing application of some embodimentsstores camera archives in a particular location within the folderstructure set up by the application. FIG. 34 illustrates the filenavigation GUI 1200 of some embodiments with the archives folderselected in column 1210. As this shows, some embodiments store thearchives separate from the events (the media assets and associated mediafiles) and the projects (the user-created composite presentations).

Although each archive includes one or more media files, the fourarchives listed in column 1215 of the file navigation GUI 1200 are shownas files, but without file extensions. As mentioned, some embodimentsstore the archives as bundles, which are a set of files that appear likea single file to a user. In some embodiments, a user can view thecontents of a bundle by selecting the bundle, then selecting an option(e.g., from a drop-down menu) to view the bundle's contents. However,the bundle format prevents a user from easily accessing the files in thebundle and accidentally modifying the contents of an archive.

Some embodiments use the camera archives to restore media files thathave been deleted for space-saving reasons. For instance, if a user isworking on a large project (e.g., a feature film), the project mayinvolve the use of hundreds or thousands of GBs of media. Rather thanstoring all of this media (in multiple encoded forms) in the filestorage for the application, the media-editing application may enablethe user to delete the media, while retaining the event and clip datastructures (e.g., as a menu option), in order to create offline clips(or offline events and/or projects). The user can store camera archives(e.g., on a set of external hard drives), and then re-import the mediafiles from the camera archive when time comes to return to the project(e.g., if making a director's cut of a film a few years after theoriginal release). Because the media asset data structure stores theUUID of the media files to which they refer, the newly-imported mediacan be easily matched with its appropriate asset by the media-editingapplication.

Ii. Scheduling Engine

Much of the discussion above in Section I described the import of mediafiles (especially video files, and the parallel processing of thosefiles at import (e.g., to transcode the media, analyze the media, etc.).In some embodiments, the user can select to perform any of the transcodeor analysis options on a media file at any time after import of themedia file as well, including during playback of the media file. Thesame architecture of the media-editing application will perform theseoperations whether performed at time of import or post-import.

A. Scheduling of Operations

The media-editing application of some embodiments includes a schedulingengine that manages the preparation of images (e.g., video images) forvarious destinations, including the transcoding and analysisdestinations described above (as well as other size transcodes ordifferent types of analysis). In addition, some embodiments use the sameengine to manage the preparation of images for playback (e.g., playingthe image back in the preview display area or a thumbnail filmstrip).

Whenever possible, the scheduling engine of some embodiments ensuresthat each image is only read once from the disk on which its media fileis stored and then only decoded once, rather than performing thesefunctions separately for each destination. In addition, in someembodiments the scheduling engine manages graphics processing operationsthat prepare the image for its destinations, and seeks out efficienciesthat can be realized in these operations. As different destinations mayneed an image in different resolutions, colorspaces, etc., some graphicsprocessing may be required before sending the decoded image to thedestinations. For instance, if two destinations process an image in thesame format, then any graphics processing operations can be done onlyonce. If, on the other hand, two destinations process the image indifferent colorspaces, then operations to convert the image into thosetwo colorspaces must be done separately and different image data sent tothe two destinations. In addition to conversions between colorspaces,resolutions, etc., the graphics processing may include blend,compositing, etc. operations in some embodiments to prepare an image foroutput using multiple source media files, as well as the application ofone or more effects (e.g., stored in an effects stack) to an image.

FIG. 35 conceptually illustrates a process 3500 of some embodiments forpreparing images of a media file for one or more processingdestinations. These destinations may be analysis operations (e.g.,person detection, shake detection, color balancing, etc.), encodingoperations (e.g., different encoders for different size files, differentencoders using different formats for presentation or storage indifferent locations, etc.), or real-time playback-related operations(e.g., display on a monitor or other display device, associated videowaveforms or histograms, etc.), as well as any other destinations thatuse the images of a media file. In some embodiments, some or all of theprocess 3500 is performed by the scheduling engine of a media-editingapplication, also referred to as a playback engine.

As shown, the process begins by receiving (at 3505) a set ofdestinations for a media file. These destinations may be user-selectedanalysis and encoding options received through a GUI such as thatillustrated in FIG. 4. The set of destinations may also includepost-import destinations such as a background rendering operation thatpre-renders portions of a project in the timeline. The destinations mayalso include one or more playback-related destinations, such as anoutput to a monitor or other display device. The output may be at one ormore different sizes (e.g., displaying an image in both a thumbnailfilmstrip clip representation and a preview display area).

The process identifies (at 3510) the required format for eachdestination. Identifying the formats ahead of time allows themedia-editing application to identify destinations that require the sameformat image and only generate one image in that format for thedestinations. In addition, some embodiments identify destinations thatrequire images that are partially the same format, such as when twodestinations require images in different sizes, but the same colorspace,or different colorspaces and the same size.

With the formats identified for the various destinations, the processselects (at 3515) an image of a media file. When playing back orskimming a video, the selected image will be whichever image of thatvideo file is requested by the display. If the user is skimming throughthe video, then the images may not actually be requested in timesequential order (e.g., if the user is skimming backwards through thevideo). In addition, the user might be moving a playhead across thevideo too fast to display every image in the media file. When playingback the video, the application will generally try to display everyimage at the frame rate of the video (e.g., 24 frames per second, etc.).However, as described further below, the scheduling engine of someembodiments will skip images when necessary to keep up with playbackrequirements. When no real-time destinations are involved (e.g., theapplication is transcoding and analyzing the images, either at import ora later time), some embodiments select the images in time-sequentialorder.

The process 3500 then reads (at 3520) the selected image from the disk.In some embodiments, this operation is not actually performed by thescheduling engine of the media-editing application, but rather a requestfor a disk read operation is sent to a processor of the device on whichthe application is operating, and the processor performs this disk readoperation in coordination with its own scheduler and the operatingsystem. That is, the scheduling engine prioritizes its operations, andthe processor then makes the decisions as to which threads to run inwhich order using both the priorities assigned by the scheduling engineand the processor's local knowledge of resource availability.

After the image is read from the disk, the process 3500 determines (at3525) whether any destinations need the image in the format in which itis stored on the disk. This will often be an encoded format, such thatmost destinations will need the image to be decoded, but if the image isstored as raw pixel data (which will generally be a very large file),then some destinations may want that raw pixel data with no formatconversions necessary. In addition, some destinations might want theimage in its encoded form. When any such destinations exist, the processsends (at 3530) the image to these destinations prior to decode, ratherthan decoding and then re-encoding the image in the same format.

Next, the process decodes (at 3535) the image. If the image is actuallyraw, unencoded pixel data, then the process will of course skip thisoperation. However, media is often stored in an encoded format, andtherefore will need to be decoded for a destination to perform itsoperations on an image. As with the disk read operation, in someembodiments the decode operation is actually performed by the processor(or a separate decoder hardware), and the scheduling engine of themedia-editing application schedules this operation. While FIG. 35illustrates a linear flow for each image in the media file, someembodiments will issue a disk read operation for one image when aprevious image has not yet been decoded and sent to the requesteddestinations, in order to keep a buffer of images at each operation andavoid wasted time.

With an image decoded, the process 3500 can begin to send the image toits destinations. The process selects (at 3540) a destination from thereceived set of destinations to which the media file should be sent. Insome embodiments, the media-editing application stores an ordered listof all its possible destinations, and sends the image to thesedestinations in the order specified by the list. Some embodimentsprioritize playback ahead of other destinations, as the playback isdependent on the images arriving at a particular rate, whereas otherdestinations can handle delays.

The process then generates (at 3545) an image for the selecteddestination. This image will be in the format required by thedestination, as identified at operation 3510. Generating the image mayinvolve performing colorspace conversions on the pixel data, resamplingthe pixels at a different resolution, etc. In some embodiments,resampling the pixels uses one or more pixel transforms to scale theimage data to the correct size, as described in detail below in SectionV. The image generation may also involve additional graphics processingoperations such as blends between multiple images, compositing multipleimages together, etc. In this case, the scheduling engine may need toschedule multiple disk reads and decodes to generate a single compositeimage for the destinations. In general, these sorts of operations arenecessary for post-import destinations such as background rendering,display, etc., rather than for import destinations such as transcodingor single-file analysis.

In some embodiments, as with the disk read and decode, the formatconversion operations are scheduled by the scheduling engine andperformed by a processor. Depending on the conversion operation and thedestination, some embodiments may use a graphics processor of the devicerather than a central processor. Some embodiments use both types ofprocessor (CPU or GPU) depending on the operation to perform.

With the image generated in the appropriate format for the currentlyselected destination, the process sends (at 3550) the image to theselected destination. That is, in some embodiments, the schedulingdestination instructs the format conversion operation to send its outputto the appropriate destination. In some embodiments, the image data isstored in a cache on the processor or in volatile storage (e.g., RAM),and the scheduling engine instructs the destination to perform itsoperation on the image data stored in that particular location.

The process also determines (at 3555) whether any additionaldestinations need the image in this same format. In some cases, forexample, multiple analysis operations might all want to use the samedata (e.g., color balancing and person detection). When additionaldestinations required the image, the process sends (at 3560) the imageto the additional destinations. In some embodiments, this involvesinstructing multiple destination operations as to the location (e.g., ina cache, in RAM, etc.) of the image data. In some embodiments, theinstructions also indicate that other destinations are using the imagedata, and therefore the data should not be overwritten until allnecessary destinations have accessed the data.

After sending the particular format image to all of its destinations,the process determines (at 3565) whether any additional destinationsremain for the current image that need the image in a different format.If additional destinations remain, the process returns to 3540 to selectanother destination, and will cycle through operations 3540-3565 untilall of the necessary format conversions are performed and alldestinations have received the image in the appropriate format.

Once the process 3500 has sent the image to all of the destinations, theprocess determines (at 3570) whether more images from the media file areneeded. When performing one or more transcode or analysis operations,the process will generally analyze each image in the media file.However, when a user is playing back or skimming a clip, not all of theimages may be needed. A user might pause playback, only play a portionof the media file represented by the clip, skim through a short sectionof the media file, etc. If additional images are required, the processreturns to 3515 to select a next image. Once no more images are needed,the process ends.

While operations 3540-3565 illustrate a linear flow that cycles throughthe destinations based on the required input format of the destinations,some embodiments actually use a tree structure to realize additionalefficiencies in the format conversion. When two destinations requireimages of the same size, but in different colorspaces, the schedulingengine may schedule a size conversion first, then two differentcolorspace conversions (or only one, if the image values are already inone of the required colorspaces), as opposed to completely separatingthe processing for each destination. This tree structure for theoperations will be described in detail by reference FIGS. 36 and 37.

FIG. 36 conceptually illustrates the software architecture of a system3600, and may involve operations performed both by the operating systemof a device (e.g., a disk read operation) as well as by themedia-editing application of some embodiments that runs on the device(e.g., the scheduling operations). Some of the modules and operationsshown in system 3600 are similar to those shown in FIG. 1, specificallythe scheduling engine 3605, disk reader 3610, and decoder 3615. Thesystem 3600 also includes four output destinations and two imageprocessing operations. One of ordinary skill will recognize that thesedestinations and image processing operations are not the only operationsthat such a system would necessarily include, but rather represent oneset of operations that might be performed in parallel. FIG. 37,described below, illustrates the system 3600 with different operationsfor different destinations. Which operations are performed by the systemdepends on which actions are performed/requested by a user of themedia-editing application.

In this figure, the four destinations include a first encoder 3620, asecond encoder 3625, a person detector 3630, and a color balancer 3635.This represents a set of operations that the media-editing applicationmight perform during import of a set of media files (e.g., from acamera), though the operations could also be performed at a later timeafter import (e.g., upon returning from the field to a computer withhigher processing power after importing the files while on a laptop).The two encoder destinations 3620 and 3625 encode different size images.In some embodiments, the two encoders are actually the same destination(i.e., perform the same encoding algorithm), but receive two differentsize images. Other embodiments use different encoding algorithms (e.g.,ProRes 422 and ProRes Proxy encoding) and may even use differentencoders (e.g., different encoder hardware). The person detector 3630and color balancer 3635 are analysis destinations that generate analysisdata about a received image.

The two image processing operations 3640 and 3645 are performed by theCPU and/or GPU of the device on which the media-editing applicationoperates in accordance with scheduler instructions in some embodiments.The operation 3640 is an operation to modify the resolution of areceived image to one-fourth the size (e.g., from 1920×1080 pixels to960×540 pixels), while the operation 3645 converts an image to full size(e.g., 1920×1080 pixels) if the image is not already that size, andconverts the image colorspace to Y′CbCr (as the image will often bereceived in the RGB colorspace of the device that captured and recordedthe image).

The disk reader 3610 and decoder 3615 are described in detail above byreference to FIG. 1 and FIG. 10. In short, the disk reader 3610retrieves image data for an image from a media file stored on a physicalstorage device, such as an internal or external hard drive. The decoder3615 performs a decode operation to convert the image data from anencoded form to a pixel buffer (i.e., an ordered set of pixel values).The media storage 3650 stores the media files used by the media-editingapplication. The media storage 3650 may represent a single physicalstorage device (and even a single organized set of file folders on thephysical storage device), or multiple storage devices (e.g., internaland external hard drives, network drives, etc.).

The operation of the system 3600 will now be described. When thescheduling engine 3605 determines that an image is needed, the engine3605 schedules a disk read operation with the disk reader 3610. Thescheduling engine 3605 of some embodiments has a clock (either areal-time clock or a value clocked by non-real-time destinations, asdescribed below by reference to FIGS. 39-42), and uses this clock todetermine when to schedule various different operations. In addition,the scheduling engine may receive input (e.g., from a user interface asshown above in FIG. 10) that indicates which images should be sent tothe various destinations.

FIG. 36 illustrates that an encoded image 3655 is read from the mediastorage 3650 by the disk reader 3610. The disk reader sends this encodedimage 3655 to the decoder 3615. In some embodiments, a processorperforms the disk read operation and the encoded image data is stored inthe cache of the processor, from which the decoder will read the data.

The operation of the decoder 3615 is also scheduled by the schedulingengine 3605, based on the same factors that the engine 3605 uses toschedule the disk read operations in some embodiments. As with the diskread operation, the decode operation is performed by the processor insome embodiments. In some cases, the operating system of the devicerunning the media-editing application includes various codecs fordecoding images in various formats, and the appropriate codec is used todecode the encoded image 3655. In some embodiments, specific decoderhardware is used to perform the decode operation.

The output of the decoder 3615 is a decoded image 3660. In someembodiments, this is an ordered set of pixel data (e.g., valuesindicating each pixel's color in a colorspace). As with the encodedimage 3655 output by the disk read operation, the decoded image 3660 maybe stored to a cache on the processor, volatile storage such as RAM, ora different storage in different embodiments.

As shown, the decoded image 3660 is sent to multiple differentoperations. The image is sent directly to the second encoder 3625, whichuses the decoded data without any intermediate operations. As shown,this encoder outputs an encoded image 3665 that is stored in the mediastorage. This encoded image will generally be in a different form thanthe encoded image 3655, as otherwise the transcoding operation will be awaste of time. In some embodiments, the full-size encoder uses ProRes422 encoding.

The other destinations (the first encoder 3620, the person detector3630, and the color balancer 3635) all require the system to perform oneor more image processing operations on the decoded image before sendingthe decoded image to the destination. For instance, operation 3640 isperformed on the image 3660 to reduce its size by one-fourth. In someembodiments, this involves resampling the pixels in such a way as todetermine the ideal pixel values for each of the new pixels (whichencompasses four of the pixel values in image 3660). The output of thisoperation 3640 is a quarter-resolution image 3680 that is sent to thefirst encoder 3620. The first encoder 3620 outputs an encoded image 3670that is stored in the media storage. In some embodiments, the firstencoder uses ProRes Proxy encoding.

In addition, operation 3645 is performed on the image 3660 to transformthe color space of the image into the Y′CbCr colorspace. If the decodedimage 3660 is not at full-size, the operation 3645 also performs ascaling operation, similar to that of operation 3640. In someembodiments, a full-size image is a 1920×1080 image. The output Y′CbCrimage 3675 is sent to the person detector 3630 and color balancer 3635for analysis. The function of these operations is described above inSection I.

As shown, the scheduling engine 3605 also manages the image processingoperations 3640 and 3645 in some embodiments. The scheduling engine ofsome embodiments schedules the image processing operations required toconvert a decoded image into the proper format for display. Theseoperations may be performed by a CPU or a GPU in some embodiments. Insome embodiments, the image processing operations are performed by arendering engine that is specifically designed for image renderingoperations, and each of the operations is a node in a render graph forthe operation.

FIG. 37 conceptually illustrates a different set of operations performedby the system 3600. As in FIG. 36, the scheduling engine 3605 managesthe disk reader 3610 and decoder 3615 to read an image 3755 from themedia storage 3650 and decode the image in order to generate a decodedimage 3760 (i.e., raw pixel data).

FIG. 37 illustrates a scenario for system 3600 in which themedia-editing application is playing back a media file on the display(the on-screen playback destination 3720) as well as generating anddisplaying a video histogram 3725 and a video waveform 3730. Each ofthese destinations requires a different image format, but that does notcompletely prevent the realization of efficiencies in the post-decodegraphics processing.

The on-screen playback 3720 (e.g., playback in the preview display area)needs a 960×540 image in this case (due to the size of the playbackarea), in the RGB colorspace of the display device (display devices mayhave slight differences in their colorspaces). As such, the decodedimage is sent to operation 3735, which performs a scaling operation toreduce the size of the image by one-fourth (similar to operation 3640)and transforms the colorspace of the image. This operation outputs animage 3775, which is sent to the on-screen playback destination 3720 fordisplay (e.g., in the user interface of the media-editing application).In some embodiments, the image will be displayed in multiple locationswithin the user interface (e.g., the preview display area and athumbnail filmstrip). In this case, a single colorspace conversion maybe performed, followed by two different scaling operations.

The video histogram 3725 and video waveform 3730 both use a 1280×720image, but require the image to be in different colorspaces. As such,the decoded image is sent to the size conversion operation 3740, whichoutputs a 1280×720 image. This resized image is sent to a pair ofcolorspace conversions 3745 and 3750 for the different destinations 3725and 3730. The conversion operation 3740 is similar to the scalingoperation performed at 3735. All of the scaling operations shown inthese two figures keep the pixel aspect ratio at 1:1 and do not modifythe image aspect ratio. However, in some cases a conform operation willbe needed that changes the image aspect ratio and/or pixel aspect ratio(e.g., converting a 1920×1080 HD image with 16:9 image aspect ratio toan 720×480 SD image with 4:3 image aspect ratio).

The image processing operations 3745 and 3750 take the 1280×720 image3780 and convert the image to the appropriate colorspace for the videohistogram 3725 and the video waveform 3730, respectively. The videohistogram, in some embodiments, displays a histogram of RGB values foran image (i.e., the number of pixels having each R, G, and B value). Thevideo waveform, in some embodiments, shows luma and/or chroma values ateach x-coordinate of an image. As such, the histogram requires an image3765 in RGB colorspace, while the waveform requires an image 3770 inY′CbCr colorspace.

FIGS. 36 and 37 each illustrate a particular set of operations performedby the system 3600 of some embodiments. One of ordinary skill in the artwill recognize that in different embodiments, the various destinationswill require images with different sizes and different colorspaces. Forinstance, the person detector and color balancer might not both operateon a Y′CbCr image in some embodiments, and the video histogram andwaveform might always operate on an image the same size as the on-screenplayback in some embodiments. However, regardless of the particularimage conversions shown in these figures, the scheduling engine of someembodiments will generally identify destinations requiring similar imageformats and fan-out the image processing as late as possible in order tomaximize the efficiency of the image processing. In addition, one ofordinary skill will recognize that the examples shown in FIGS. 36 and 37are only two examples of many possible sets of destination operationsand intermediate processing operations that might be required by amedia-editing application. For example, the system shown in FIG. 36might also include a shake detection operation, which in someembodiments requires multiple images at a time for comparison. Thereal-time operations shown in FIG. 37 might need graphics processingoperations in the render graph that transform and/or composite multipleimages into a single image (e.g., a picture-in-picture image).

B. Clocking the Scheduling Engine

As mentioned in the above discussion, the scheduling engine of themedia-editing application of some embodiments uses different clockingmechanisms depending on whether any of the image destinations is areal-time destination (i.e., video playback). Video playback willrequire particular video images at particular times, and therefore thescheduling engine will skip images if necessary. On the other hand, whenthere is no destination that has a required rate at which to receive andoutput the images, the scheduling engine will not skip images, and willprovide images to accommodate whatever rate the destinations areprocessing the images.

FIG. 38 conceptually illustrates a process 3800 for determining whichimage of a media file to display. In some embodiments, the schedulingengine of a media-editing application performs the process 3800. Asshown, the process begins (at 3805) by receiving a media file for one ormore destinations. The scheduling engine does not actually receive themedia file itself in some embodiments, but rather data indicating thefile (or portion of a file) that the application needs to display,analyze, transcode, etc. The destinations, as described above, are thetranscoding, analysis, and output destinations.

The process 3800 then determines (at 3810) whether any of thedestinations are real-time destinations. These include on-screen videoplayback, as mentioned, as well as data that accompanies such playbackin real-time, such as the video histogram, waveform, or vectorscope. Thehistogram and waveform are described in the preceding subsection, andthe vectorscope is a color wheel that indicates the distribution ofcolor in a particular image.

When there are no real-time destinations, the process proceeds to 3825,described below. If none of the destinations are real-time, then thescheduling engine does not need to worry about skipping images, becausethere is no urgency to the display of a particular image at a particulartime. To the contrary, many analysis destinations (e.g., the colorbalancer, people finder, etc.) and encoders will need to analyze eachimage in a media file.

On the other hand, when at least one of the destinations is a real-timedestination, the process 3800 determines (at 3815) whether there is aneed to skip any of the images in the media file (as opposed to simplyplaying the images in sequential order). If the user is skimming througha media clip, then the application will not be able to display all ofthe images and will choose which image to play based on real-timeupdates from the user interface indicating the location within a mediaclip to display. In addition, when playing back video at real-time, thescheduling engine will compare the progress of the playback to areal-time clock and determine whether any images should be skipped. Theusage of a clock by the scheduling engine will be described in furtherdetail below by reference to FIGS. 41 and 42.

When the scheduling engine needs to skip at least one image, the processidentifies (at 3820) the number of images to skip. This may be based onthe location of a playhead over a media clip representation throughwhich a user is skimming, or a combination of clock information andinformation about the progress of a playback operation.

The process 3800 then selects (at 3825) an image based on the determinedinformation. When there are no real-time destinations or the real-timedestinations are keeping up with the real-time clock (i.e., displayingimages at a required frame rate), the selected image is the next image.On the other hand, when the scheduling engine is skipping images, theselected image is based on the most recently selected image and thenumber of images to skip identified at 3820.

After selecting the image, the process determines (at 3830) whetheradditional images remain in the media file. When more images remain, theprocess returns to 3810 to identify the next image to select. On theother hand, when no more images remain (or the user has ceased skimmingthrough the clip representation in the media-editing application GUI),the process 3800 ends.

In some embodiments, the non-real-time destinations include a backgroundrendering operation that generates render files for segments of atimeline (e.g., portions between edit points in the timeline). Thebackground rendering operation generates an output image for each framein the timeline in some embodiments. When performing real-timeoperations such as playback and its associated operations, someembodiments read from the previously-generated render files rather thanre-generating output images, which helps ensure that the real-timeplayback skips images minimally.

The discussion of FIG. 38 indicates that the scheduling engine maybehave differently when scheduling image processing for a real-timedestination (e.g., playback) as compared to when scheduling imageprocessing solely for analysis destinations. FIGS. 39 and 41 illustratedifferent clock mechanisms that are used by the scheduling engine 3605,depending on whether one or more of the image destinations is areal-time destination or not. While these are shown as separate figures,the figures represent a single scheduling engine that is operable ineither of the two modes.

FIG. 39 illustrates scheduling engine 3605, which manages disk reader3610 and decoder 3615. For simplicity, the graphics processingoperations (e.g., colorspace conversion, size conversion, etc.) areomitted from these diagrams. FIG. 39 also illustrates a set ofdestinations 3920 including a master destination 3905, as well asadditional destinations, and an image-processing clock 3910. The masterdestination 3905 is a non-real-time destination, as are all of the otherdestinations. These destinations may be analysis destinations such aspeople detection, color balancing, shake detection, encodingdestinations, background rendering, etc., so long as the destinationsare not required to output images in real-time.

The master destination 3905 is in charge of updating the schedulingengine with its progress. In some embodiments, the destination expectedto perform its operations the slowest is designated as the masterdestination by the scheduling engine. Some embodiments include a sethierarchy of operations stored for the engine, and the highest operationon this hierarchy is designated as the master destination. Otherembodiments designate a master destination in other ways.

The image-processing clock 3910 is part of the scheduling engine in someembodiments, while in other embodiments provides data to the schedulingengine as shown in this figure. The image-processing clock is usedspecifically when there are no real-time destinations in someembodiments, and does not actually correspond to a real clock. Instead,each time the master destination 3905 completes the processing of aframe, the master destination 3905 sends an update 3915 to theimage-processing clock. This causes the image-processing clock toincrement itself by one.

The scheduling engine uses the image-processing clock to schedule itsdisk reads, decodes, and graphics processing operations in order togenerate the images required by the destinations 3920. In someembodiments, the scheduling engine initially schedules a particularnumber of images to be sent to the destinations (e.g., five, ten,twenty-five, etc.). The number of such images may be dependent on theexpected processing time for the master destination (e.g., the amount oftime expected for the person detector to detect people in an averageimage) or the slowest of the destinations. This expected processing timemay be a function of the particular destination, the processor speed andnumber of processors of the device performing the operations, as well asother factors.

Once the initial set of images are scheduled by scheduling engine 3605,the engine schedules a disk read for the next image once the imagecompletion update 3915 is received by the image processing clock 3910.In some embodiments, the image-processing clock 3910 instructs theplayback engine that the processing for the next image should bescheduled, and the scheduling engine then schedules the disk readoperation for that next image. In other embodiments, the schedulingengine periodically checks the image-processing clock to determinewhether an image has been completed by the master destination.

FIG. 40 illustrates a timeline 4000 for the scheduling engine of someembodiments when the engine is scheduling operations for non-real-timedestinations. As shown, the engine initially schedules a disk read,decode, and format conversions for frame X. In this figure, it isassumed that frame X is not in the initial set of images, but rather issomewhere in the middle of the set of images being processed. After aparticular period of time, the scheduling engine receives an update fromthe master destination indicating that the destination has completed aframe. As a result of this update, the scheduling engine schedules adisk read, decode, and format conversions for the next image, frame X+1.After a second particular period of time, which is noticeably longerthan the period of time after the frame X conversion, the enginereceives its next clock update from the master destination. Despite thedelay, the engine schedules the next image, frame X+2, upon receivingthe update.

The delay could be caused by a different application, that runs on thesame device as the media-editing application, making use of theprocessor for a period of time, thereby slowing down the media-editingapplication times. In addition, some embodiments prioritize differentoperations, with the analysis, encoding, and background renderingoperations taking place in the background and being prioritized behinduser interface and playback operations. Some embodiments pause theanalysis operations and the disk read, decode, and graphics processingthat feeds those operations when a user interacts with the media-editingapplication GUI or the application is playing back video and/or audio.In addition, some embodiments allow the user to pause these operations(for instance, to enable a different application to perform itsoperations without having to fight with the media-editing applicationfor resources).

For non-real-time destinations, some embodiments try to keep the samenumber of images in the buffer at all times, and thus start the imagepreparation for a new image each time an update is received that themaster destination has finished operations on a previous image. In thecase that the non-real-time destinations are operating faster than thescheduler can prepare images, then these destinations may have to wait.However, generally the non-real-time destinations take longer to performtheir operations than to prepare images for these operations. On theother hand, because the real-time destinations are lessprocess-intensive, but often require more image preparation (e.g.,compositing, etc.), it may be more difficult for the scheduling engineto keep up with the real-time requirement of these destinations.

FIG. 41, as mentioned, illustrates the scheduling engine 3605 in thesituation in which at least one of the destinations is a real-timedestination (in this case, real-time playback). Like FIG. 39, thisfigure illustrates the scheduling engine 3605 that manages disk reader3610 and decoder 3615, and omits the conversion operations. FIG. 41 alsoillustrates a set of destinations 4120, including a real-time playbackdestination 4105. The real-time playback destination 4105 requiresimages at a particular rate (i.e., the frame rate of the media file,often 24 fps or 30 (29.97) fps). The additional destinations will oftenbe additional real-time destinations. In some embodiments, becauseanalysis and encoding operations on a media file are veryprocessor-intensive and take significantly longer to complete thanplayback of the media file, the scheduling engine will schedule theseoperations separately from the real-time destinations even whenanalyzing the same media file that is also playing in real-time.

The real-time playback destination, as shown, outputs to an outputdevice 4110. This may be a monitor with a refresh rate (e.g., 100 Hz),an audio output device with a sampling rate (e.g., 48 kHz), etc. Thesephysical devices have their own internal clocks that operate atreal-time (to handle the refresh rate, sampling rate, etc.). In someembodiments, one such output device sends its real-time clockinformation 4115 to the scheduling engine 3605 (or a clock module thatis either a separate module such as image processing clock 3910, or partof the scheduling engine 3605) at regular intervals. Whereasimage-processing clock 3910 is used specifically for non-real-timedestinations only, the real-time clocking function is used only when atleast one destination requires images in real time. In many cases theother destinations are operations that output information correspondingto the image displayed as part of the real-time playback (e.g., a colorwaveform or color histogram).

In addition, as shown, the real-time playback destination 4105 sendsprogress updates 4125 to the scheduling engine 3605. These progressupdates 4125 indicate to the scheduling engine the status of theplayback. In some embodiments, the progress updates simply state whichimages have been output; in other embodiments, the progress updates alsoinclude additional information such as the number of images stored in anoutput buffer of the playback destination.

The scheduling engine of some embodiments uses the real-time clockinformation and the progress updates from the playback destination toschedule its disk read, decode, and graphics processing operations inorder to generate the images required by the destinations 4120. In someembodiments, the scheduling engine initially schedules a particularnumber of images to be sent to the destinations (e.g., five, ten,twenty-five, etc.). In some embodiments, this number is dependent on thebuffer size of the playback destination.

Disk reads and subsequent operations are then scheduled based on theupdates received by the scheduling engine. In some embodiments, theremay be a number of reasons for the scheduling engine to drop frames.When the system is operating properly, the scheduling engine sendsimages to the playback destination at the requested rate, and theplayback engine outputs the images at this rate. However, in some cases,the disk read, decode, and format conversion operations take too long(e.g., because the application is operating on a device without enoughprocessing capability or whose processing resources are being used byother processes). In this case, the buffer of the real-time playbackwill become empty and it will not have images to output. In other cases,the real-time playback itself will run behind, even if the schedulingengine is preparing images at the needed rate.

FIG. 42 illustrates a timeline 4200 for the first of these failuremodes. As shown, for the first image, frame X, the engine schedules adisk read, decode, and format conversions. As with timeline 4000, thisfigure assumes that frame X is not in the initial set of images that arescheduled in order to initially fill the playback buffer, but insteadare somewhere in the middle of the playback of the set of media images.The engine receives a progress update from the real-time destination,indicating its playback state, and then checks the real-time clockbefore starting the next image. At this point, the operations are beingperformed in time, so no images are skipped and the engine can beginscheduling the disk read for the frame X+1.

However, in this case, the disk read for frame X+1 takes significantlylonger to perform, and thus the scheduling engine cannot schedule thedecode for frame X+1 as quickly as it would ideally. The decode alsotakes longer for frame X+1 than for the previous frame X, so that it hasalready received a progress update from the real-time destination beforescheduling the conversions for frame X+1. At this point, the schedulingengine checks the real-time clock and determines that its scheduling isrunning behind the real-time requirement of the playback destination. Assuch, the engine next schedules a disk read for frame X+3, thus skippingan image in its processing. As noted, this illustrates the situation inwhich the disk read, decode, and graphics processing operations areunable to output images at the rate needed for playback, and thus images(in this case, frame X+2) are skipped (i.e., dropped). In many cases,for instance due to a spike in processor use by a different application,the scheduling engine will be required to skip numerous images, ratherthan just one image.

These timelines indicate a linear flow through the processingoperations, in which all of the operations for a particular image areperformed before moving onto the next image. In some embodiments, thescheduling engine actually schedules operations for later frames wellbefore all of the processing operations for earlier frames havecompleted. As one example, the engine might schedule a disk read forframe 500, and then next schedule a decode for frame 475 and formatconversion for frame 400. In addition, the scheduling engine may bescheduling disk reads and decodes from multiple different source filesin order to create a single output image (e.g., when playing back acomposited image). In such a case, the engine of some embodimentsschedules separate disk reads and decodes for the source files based onan order indicated by a render graph for the output image. The rendergraph may indicate a compositing order (i.e., blend images A and B, thencomposite the blend with image C) for the various images, and thescheduling engine schedules the preparation of the images according tothe compositing order.

III. Real-Time Editing and Playback

As described in the previous section, the scheduling engine of someembodiments determines which image of a media file should be output andschedules various operations to perform on the image in order to preparethe image for its output. These operations include reading the image inits encoded form from a disk, decoding the image, and performinggraphics processing on the image (e.g., scaling the image, conformingthe image, changing the colorspace, etc.).

Some embodiments include the ability, during playback, to dynamicallyrespond to changes in a timeline that the media-editing application isplaying back. As one example, a user might start the playback of aproject (i.e., a composite presentation having multiple media clips) andthen modify the project during the course of the playback. As theplayhead moves through the timeline, the media-editing application playsthe portion of the media file indicated by the project data at thattime. In some embodiments, the application will work ahead and haveimages prepared for the upcoming media. However, if the user modifiesthat timeline during the course of the playback, the scheduling engineof some embodiments will schedule new operations so as to play the mostupdated version of the timeline. In some cases, as a user moves ananchored clip along a timeline such that the movement of the anchoredclip intersects the playhead, the application will begin playing theanchored clip as soon as it intersects the playhead. When a clip isanchored above the primary timeline (also called the spine), theanchored clip will take precedence over clips at the same time in theprimary timeline. Thus, when the playhead intersects an anchored clip,it will play the anchored clip. This assumes the anchored clip fills theoutput image and has not been transformed to take up only a portion ofthe output image, as well as that the anchored clip is opaque (i.e.,does not have any transparency). In such a case, the application willplay the composite image.

FIG. 43 conceptually illustrates the software architecture of a system4300 that enables such dynamic modification of the output. As with FIGS.36 and 37 above, the system includes scheduling engine 3605, disk reader3610, and decoder 3615, the operation of which has been described indetail above. FIG. 43 illustrates only one destination for simplicity,the on-screen playback 4305, for which a resize and conversion to thedisplay device RGB colorspace is performed by operation 4310 (which mayactually be separate operations in some embodiments).

The system 4300 also includes a playback media identifier 4315, a userinterface 4320, and project data 4325. The project data 4325 is the datastored by the media-editing application about one or more projects,including a project being played back in the timeline. In someembodiments, the application stores the data for a particular projectusing the clip object data structures that are described above inSection I.E, which indicate all of the media used in the project as wellas the hierarchy, compositing, timing, effect, etc. information aboutthese clips that indicate how the clips are put together to create theproject.

Through the user interface 4320, the user makes modifications to theproject displayed in the timeline. The user interface processes userinteraction, displays the results of the user interactions, and modifiesthe project data 4325 in accordance with the user interactions. Theseuser interactions might include adding clips to the timeline, movingclips in the timeline, removing clips from the timeline, trimming clips,adding effects to clips in the timeline, transforming clips, etc.

The playback media identifier 4315 reads the current project state fromthe project data 4325 and informs the scheduling engine as to whichimage it should be scheduling and the source file for that image. Thatis, the playback media identifier 4315 identifies the upcoming mediaclips in the timeline based on the current location of the playhead, andfrom these identifies the media assets referenced by the upcoming mediaclips. These media assets in turn reference media files, and the rangeinformation stored in the media clips determine which portions of themedia files should be read. Thus, the playback media identifier 4315 canrequest specific images from specific source files (i.e., images havinga particular timecode in the source file). In some embodiments, theplayback media identifier 4315 is actually a part of the schedulingengine 3605, rather than a separate module as shown.

The operation of the system 4300 will now be described. When a userinteracts with the user interface 4320 by modifying the timelinedisplayed in the GUI, the user interface modifies the project data 4325of the project currently displayed in the timeline. In addition, theuser interface 4320 sends an edit notification to the scheduling engine3605. This informs the scheduling engine that it will need to re-checkthe project data 4325 because the data has changed. In some embodiments,the scheduling engine reviews the project data, using the playback mediaidentifier 4315, and schedules the playback ahead of time.

Some embodiments render portions of the project shown in the timelineahead of time as the playhead moves through the timeline (i.e., fasterthan real-time), or render the project shown in the timeline in thebackground when not performing other actions, then store these renderfiles either in volatile memory (e.g., RAM) or in the application folderstructure. When portions of a project have been rendered ahead, thestored render files may be used for output. However, when a user ismodifying the project in the timeline, such files may not be available.An example case of such user modification occurs when a user moves ananchored (e.g., B-Roll) clip across the playhead.

Upon receiving the edit notification 4330 from the user interface, thescheduling engine 3605 asks the playback media identifier 4315 for anupdate to the images (and their source files) that it will now need toschedule. The playback media identifier retrieves the current playbackstate 4335 from the project data 4325 (which is modified as the editsare made) and identifies the upcoming images for the scheduling engine3605. Using this information, the scheduling engine 3605 can scheduledisk reads, decodes, and format conversions for upcoming images. In someembodiments, the engine is predictive, and recognizes that the user ismoving the anchored clip towards the playhead. Based on the movement,the playback media identifier recognizes that the anchored clip islikely to intersect the playhead shortly, and thus the scheduling engineis able to start performing disk reads, decodes, etc. for the movingclip's underlying media in advance of the actual intersection in the GUIof the clip and the playhead. When the clip and playhead intersect, theimages have already been prepared for output. In addition, when themoving clip completely overrides the clips in the primary lane (i.e.,the anchored clip is not transformed or composited with the primary laneclips), some embodiments recognize that the output image is the sameregardless of where the clip is moved, and therefore will use anypreviously-generated background rendered files for the moving clip todisplay the clip.

FIG. 44 illustrates a GUI 4400 of a media-editing application thatdisplays such results of editing operations in the preview display areaas the user performs the editing operations. Specifically, FIG. 44illustrates the GUI 4400 in three different stages 4405-4415 as a usermoves an anchored clip 4425 along a timeline 4430 such that itintersects with the playhead 4435 that is moving through the timeline.The GUI 4400 includes similar features to those described above byreference to FIG. 3: a clip library and browser 4440, a preview displayarea 4420, and a timeline 4430.

The media-editing application of some embodiments allows the user toedit a media presentation by moving a media clip from one location toanother location within a timeline or from an area out of the timelineinto the timeline. For instance, the user can drag a media clip from theclip browser 4440 into a central compositing lane 4445 (i.e., the spine)or into an anchored lane. Some embodiments show the composite result ofthe editing operation performed by moving media clips as the operationsare being performed. More specifically, the media-editing application ofsome embodiments displays in the preview display area 4420 a compositeimage represented by a point along the timeline 4430 as the playhead4435 moves to the point and intersects with a media clip that is beingmoved.

As the playhead 4435 moves along the timeline 4430 (i.e., as themedia-editing application plays back the media presentation), themedia-editing application displays a composite frame of the mediapresentation represented by a point along the timeline 4430 at which theplayhead 4435 is positioned at that moment. When any part of a mediaclip occupies a point along the timeline 4430 at the moment the playhead4435 is passing the point, the media-editing application will factorthat media clip into the composite image displayed for that point. Whena media clip is in an anchor lane above the primary lane, the outputimage will be that of the anchor lane (unless there is a blend or othercompositing operation defined between the two images).

In the first stage 4405, the timeline 4430 displays an anchored mediaclip 4425 and media clips 4426-4429 and 4431 within the primarycompositing lane. At this point, the media-editing application isplaying back the media presentation and thus the playhead 4435 is movingto the right through the timeline 4430. The playhead 4435 currently isin the middle of the media clip 4426, and thus the preview display area4420 displays an image of the media clip 4426 that corresponds to theportion of the media clip at which the playhead is currently located.

In the second stage 4410, the user has selected the media clip 4425 andis dragging the media clip 4425 to the left such that the playhead thatis moving to the right intersects with the media clip 4425. As the clip4425 is in the anchor lane, the preview display area 4420 displays theimage from this clip, rather than clip 4428. At this point, the playhead4435 is continuing to move to the right to play the presentation. Insome embodiments, as soon as the playhead intersects the front edge (inpoint) of clip 4425, the playback image displayed in the preview displayarea changes to that of the anchored clip 4425.

In the third stage 4415, the user is dragging the media clip 4425 to theright along with the playhead 4435. As with stage 4410, themedia-editing application displays an image from the media filerepresented by clip 4425 in the preview display area 4420. This is adifferent image than shown at stage 4410, as the playhead is locatedover a different portion of the clip 4425. In theory, a user could dragthe anchored clip to the right at the same rate as the playhead, and theapplication would display the same image in the preview display area thewhole time.

FIG. 45 conceptually illustrates a process 4500 for incorporating editsinto playback of a video sequence in real-time. In some embodiments,some or all of the process 4500 is performed by a media-editingapplication's scheduling engine, user interface, and associatedfunctions. As shown, the process 4500 begins by receiving (at 4505) aproject playback command. In some embodiments, the user commands themedia-editing application to play back the contents of the timeline. Theplayback may start at the current location of the playhead in thetimeline, or at the beginning of the project (i.e., time=0).

The process moves (at 4510) the playhead in the timeline. Themedia-editing application displays the movement of the playhead at arate representative of real time. That is, in a particular amount ofactual time, the playhead moves over a portion of the timelinerepresentative of that particular amount of time. In this process, theoperation 4510 indicates a movement of one image (i.e., 1/24^(th) of asecond for 24 fps video) in the timeline.

The process also identifies (at 4515) the next image from the projectdata. In some embodiments, the project data is kept up to date withupdates to the project as the user modifies the clips in the project.When playing back a project, the application makes sure that the imagebeing displayed is the correct image for the most up-to-date version ofthe project data. In some embodiments, when the project data changes,the scheduling engine that manages the images for display receives anindication that this change has been made and retrieves the new projectdata (i.e., as shown in FIG. 43 above). These changes may includemovement of clips in the timeline, adding clips to the timeline,removing clips from the timeline, adding effects to clips, etc.

With the image identified, the process 4500 performs (at 4520)operations required to display the image in the preview display area.This may involve a disk read operation, decode operation, any graphicsprocessing operations to generate a proper format image or combineimages, etc. In some embodiments, the image will have already beengenerated by a background rendering process or by pre-rendering duringplayback and at this stage the application just reads the generatedimage (e.g., from memory) and outputs the image.

The process then determines (at 4525) whether any more images need to beplayed back. If the user pauses the playback, then (at leasttemporarily) the application can cease outputting images. In addition,if the playhead reaches the end of the timeline, then playback willcease unless the user has set the application to playback the timelinein a continuous loop. When no more images remain, the process 4500 ends.

When additional images remain, the process determines (at 4530) whetherany user edits to the timeline are being received. These edits may bethe addition of effects, transitions, titles, etc., the movement ofclips, trimming of clips, removal of clips, or other edits that affectthe project displayed in the timeline.

When no such edits are received, the process returns directly to 4510 tomove the playhead and identify the next image. However, when edits arereceived, the process displays (at 4535) a modified timeline andmodifies (at 4540) the project data. The modified display may involvethe movement of a clip, the indication of an effect, etc. With themodification performed, the process proceeds to 4510 to move theplayhead and identify the next image.

IV. Project Library and Missing Media

As described in Section I.E above, the media-editing application of someembodiments stores a set of data structures that include assets storedin events and a hierarchy of clips that refer to those assets. Inaddition to the component clips (that directly refer to a single asset),some embodiments include compound clips. Compound clips are clips thatappear as a single clip when inserted into a larger presentation, butactually contain multiple clips and can be edited in the same way as apresentation. Some embodiments use the same clip data structure for thecompound clips as for component clips.

In addition, some embodiments allow the user to define projects. Asdescribed above, some embodiments store a project as a separate class ofdata structure, similar to an event but with only one sequence datastructure for the project. Some embodiments store properties of theproject in this data structure (e.g., the video properties such as framerate, video format, etc.), though others assign these properties to thesequence data structure for the project. A project will have a specificdesignation as such, and some embodiments include a project library thatallows users to view an overview of their projects, and switch betweenprojects. FIGS. 46-51 illustrate the use of the project library forvarious tasks, including creating a new project and restoring missingreferences in a project.

FIG. 46 illustrates the creation of a new project in the GUI of amedia-editing application of some embodiments using the project library4600 in three stages 4610-4630. Specifically, the stages illustrate theopening of a project creation dialog box 4605 and the use of that dialogbox to create the new project.

The first stage 4610 illustrates the project library 4600, whichoccupies a portion of the media-editing application GUI (similar to theGUI 300 of FIG. 3). In some embodiments, the project library isinterchangeable with the timeline (i.e., the application will eitherdisplay the timeline or the project library in the bottom of the GUI).In this example, the GUI includes a project library toggle item 4615that allows a user to toggle between the timeline and the projectlibrary in this section of the GUI and a new project user interface item4625 the selection of which begins the process for creating a newproject. Some embodiments provide these options as different types ofselectable items, as menu selections, as hotkey selections, or acombination thereof.

The project library 4600 displays a list of projects at its left side.In this case, there are two projects that have been previously created.For each project, the library displays a filmstrip as a set of imagesfor the project. In some embodiments, these images represent frames fromthe composite presentation that are evenly spaced throughout theproject. As shown at stage 4610, the user has placed a cursor over thenew project user interface item 4625 and selected this item, in order tocreate a new project.

The second stage 4620 illustrates a dialog box 4605 that appears whenthe user selects the item 4625. This dialog box allows the user to enterinformation about a new project. The user can enter a name for theproject (in this case, “Proj 2”), select a default event for theproject, and set video properties, render properties, and audioproperties. The default event, in some embodiments, is the event towhich the project automatically imports a media file when a user editsthe media file into the project from a source other than an event. Forinstance, a user might drag and drop a video or audio file (e.g., fromtheir desktop or other folder) into the timeline for a project. Doingso, in some embodiments, will cause the application to automaticallyimport the file as an asset of the default event and create therequisite data structures for the media file (as opposed to prohibitingthe action or querying the user for a desired event).

As shown, the user can also either select to use the video properties ofthe first clip added to the project as the video properties for theproject, or choose custom properties. In this case, the user has chosencustom properties. The format field lets the user choose a format (e.g.,1080p, 1080i, 720p, various standard definition formats, etc.) for theproject. The options presented in the resolution and rate fields aredependent on the selected format. For the selected 1080i, for example,the resolution options are 1920×1080, 1440×1080, and 1280×1080, and avariety of frame rates are available.

The audio and render properties include a render format (in this case,the user has chosen Apple ProRes 422, though other options areavailable). The render format, in some embodiments, is the encodingformat used for cache files that are prepared to simplify playback(i.e., prepared ahead of time and used during playback). The audioproperties include an audio sample rate, and the choice between surroundand stereo for audio channels. The user can also choose to use thesettings from the most recently created project.

The third stage 4630 illustrates the result of the user selecting OK inthe dialog box 4605 in order to create the new project “Proj 2”. Theproject library now shows a third project, the newly created “Proj 2”.At this point, the user has not yet added any media clips to theproject, so the filmstrip is blank.

FIG. 47 illustrates two stages 4710 and 4720 of a timeline 4700 (similarto the timeline 315 of FIG. 3) showing the result of deleting clips froman event that are referenced by the project displayed in the timeline.As shown in project information display area 4705, the timeline isdisplaying “Proj 2”. To arrive at the first stage 4710, the user couldhave selected the project library toggle item 4615 to close the projectlibrary and display the timeline 4700 in the same place in themedia-editing application GUI as the project library was displayed, thenadded clips from the clip browser to the project. The user has addedthree clips to the primary compositing lane as well as two anchoredclips 4725 and 4735.

The second stage 4720 illustrates the timeline 4700 at a later stage atwhich point the project is unable to find the assets associated with thetwo anchored clips 4725 and 4735. As described above, each clip includesan asset reference that stores an event ID and an asset ID. The clipswill appear as missing when the event cannot be located (e.g., if theuser has deleted the event), if the asset cannot be located (e.g., ifthe user has deleted the asset from the event (by deleting the clipcontaining the asset)), or if the particular file cannot be located(e.g., because the user has deleted the file or because the applicationis using low-resolution files and none has been created for theparticular asset). In this case, a missing clip image is shown for theclips 4725 and 4735, because the user has deleted the assets that theclips reference.

FIG. 48 illustrates two stages 4810 and 4820 of a GUI 4800 that includesthe project library 4600. The first stage 4810 illustrates only theproject library 4600, which a user may have accessed from stage 4720 byselecting the project library toggle item 4615. At the locations in thefilmstrip that represent the times occupied by the missing anchoredclips, the media-editing application displays the missing clip image toindicate that the required media is unavailable. In addition, theproject library displays an exclamation icon 4805 to indicate that thereis a problem in the project. The first stage 4810 illustrates that theuser selects a toggle inspector item 4815. With the project “Proj 2”selected in the library, selecting the toggle inspector item brings upthe project inspector in inspector display area 4825 of GUI 4800, asshown at stage 4820. The information displayed in this inspector will bedescribed further by reference to FIG. 49.

FIG. 49 illustrates a workflow used in some embodiments for restoringmissing clips using the project inspector 4900, shown in three stages4910-4930. The first stage 4910 illustrates the project inspector 4900,which displays various information about the selected project “Proj 2”.The top displays the video and audio properties of the project, as wellas the default event for the project. The middle section displays thedrive on which the project data is stored, the creation date and lastmodification date of the project, and a field into which the user canenter notes about the project. The bottom section of the inspectordisplays a list of referenced events and any errors detected. In thiscase, the inspector indicates that all of the clips in the project arefrom the event “Duplicate Event” and that two clips in the event aremissing.

As the inspector indicates specifically that clips are missing, thisindicates that the application can find the event but not the clip. Whentrying to resolve a clip in a project, the application looks at theasset reference stored in the clip data structure, which stores an assetID and an event ID. The application determines an event in which theasset should be located using the event ID, then searches within thatevent to find the asset using the asset ID. As this shows that the twoclips are missing, the application has found the event “DuplicateEvent”, but two of the clips are not there (i.e., the assets aremissing).

Returning to stage 4910 of FIG. 49, the inspector displays a selectableitem 4905 labeled “Modify Event References” that provides the user withthe capability to restore the missing references if suitable assets canbe found in other events stored in the application. At this stage, theuser is selecting the reference modification item 4905.

The second stage 4920 illustrates a reference modification dialog box4915 of some embodiments displayed in response to the user selection ofitem 4905. The application detects additional events currently stored inthe application's folder structure and lets the user prioritize theevents. In some embodiments, each listed event is a selectable item thatthe user can drag up and down in order to set a priority for the events.The user can also remove events in order to exclude the use of thoseevents by the project (e.g., if the user intends to delete one of theevents, or knows that the event is unrelated to the project). As shown,the user is leaving “Duplicate Event” as the highest priority event, and“New Event 2-5-11 1” as the lower priority of the two. The applicationhas found 20 clips in “Duplicate Event” and 22 clips in “New Event2-5-11 1”.

When the user selects “Reprioritize Events”, the application searchesfor each asset referenced by the project. The application, in searchingfor a particular asset, first searches the highest priority event forthat asset, then the second highest priority event, and so on down thelist until the application finds the asset or all listed events aresearched. When the asset is found, the asset reference for the mediaclip is modified to reference the asset ID of the newly identified assetand the event ID of the event to which that asset belongs. In this case,the two missing clips are both found in the event “New Event 2-5-11 1”.

Thus, at the third stage 4930, the project inspector 4900 indicates thattwo events are referenced: “Duplicate Event” for the clips in theprimary compositing lane, and “New Event 2-5-11 1” for the anchor clips.FIG. 50 illustrates the project library 4600 now that the missing assetshave been restored. The filmstrip for “Proj 2” now displays images fromthe project through the middle, rather than displaying the missing clipimage.

FIG. 51 illustrates a similar workflow of some embodiments for restoringclips that are missing due to a missing (e.g., deleted) event, in threestages 5110-5130, using the project inspector 4900. The first stage 5110illustrates the same information as in the first stage 4910 of FIG. 49,except that rather than state that the referenced event for “Proj 2” ismissing a particular number of clips, the inspector indicates that theevent itself is missing. As in the case of FIG. 49, selecting the modifyevent references button brings up the reference modification dialog box4915 in stage 5120. This time the dialog box includes the same twoselectable items, but with the “Duplicate Event” listed as missing. Theselection of “Reprioritize Events” by the user causes the application tosearch for the assets needed for the current project (“Proj 2”) in theother events. In this case, the application finds all of the neededassets in the event “New Event 2-5-11”, and thus stage 5130 shows thatthe project inspector 4900 lists this event.

Additional failure modes may occur when an asset can be found, but theunderlying media file is unavailable. In some cases (shown below inSection V), this is because a particular size of transcoded media fileis requested but unavailable. In some cases, the original media file wasnever copied to the application, and the media clip still references afile stored on a camera. When the camera is disconnected from themedia-editing application, the application of some embodiments willindicate a missing camera failure mode.

V. Switching Between High- and Low-Resolution Editing

As shown above, the media asset data structures of some embodimentsreference both high-resolution (i.e., original media or afull-resolution transcode) and low-resolution (i.e., a low-resolutiontranscode) versions of the underlying media. The media clips refer tothese media asset data structures, but editing operations are performedon the clips irrespective of whether the actual media will be infull-resolution or low-resolution. The application generates a rendergraph for each image in a composite presentation based on the mediaclips that does not factor in which size images will be used. The assetthen acts as a multiplexer to select one or the other source files basedon the application settings. In some embodiments, this enables themedia-editing application to seamlessly switch between usinghigh-resolution and low-resolution images for playback during theediting process, without having to generate any new project data.

While this description, and much of this section, refers to an assetstoring references to two sizes of transcoded media, in some embodimentsthe asset stores references to a variety of sizes (sometimes calledrepresentations). For example, some embodiments allow a user to specifythe different media sizes that will be used, and can then switch betweenany different media sizes they have created for the media files used ina project (e.g., if the original media is captured by a cinema digitalcamera at a 4K resolution, the user might want to define a first proxyresolution of 1920×1080 and a second proxy resolution of 1280×720 andthus the asset would store references to media files for all three ofthese resolutions and the user could flexibly switch between them).

In some embodiments, regardless of the source file resolution used forplayback, a project has video properties that define an outputresolution (e.g., using the video properties for a project shown in FIG.46). The user defines editing operations (e.g., blur operations,transform operations, etc.) at this resolution, and the application willproduce output for the defined resolution. If, for example, the videoproperties define a resolution of 1920×1080, but the application uses amedia file with images having 960×540 pixels, then some embodimentstransform between the requested output image size and the source pixelsize. To enable this, some embodiments use a pixel transform thatdefines a transform between an image space (i.e., having the requestedoutput size) and a pixel space of an image. The pixel transform of someembodiments is described in detail in United States Patent PublicationNo. 2009/0244081, which is incorporated herein by reference.

A. Selection of High-Resolution and Low-Resolution Editing

Some embodiments provide a user interface feature that allows a user toquickly modify the playback quality used by the media-editingapplication. A user might want to switch to playing back video using alower resolution source file when on a computer with less processingspeed (e.g., a laptop) or while also performing various additional taskson a faster computer. For instance, if performing various analysis tasksin the background (e.g., person detection, color balancing, etc.), theuser might want to save processing and memory resources by switching tolow-resolution editing.

Some embodiments provide a set of playback quality options from which auser can select a playback quality (i.e., switch between differentresolution modes). As described above, some embodiments store up tothree versions of each media file imported by the application: a copy ofthe original media file, a high-resolution transcoded of the media file,and a low-resolution transcode of the media file.

FIG. 52 illustrates the user interface selection options of someembodiments in a menu 5200. In some embodiments, the user accesses themenu 5200 by selecting an option in the media-editing application GUI tomodify the application preferences. As shown, the menu 5200 includesselectable items for editing preferences, playback preferences(currently selected), import preferences, and debug preferences.

Within the playback preferences menu 5200, options for differentplayback options are provided. Radio buttons allow a user to selectbetween two different media sizes (low- and high-resolution). The proxymedia of some embodiments is a low-resolution transcode (e.g., 960×540pixels), while the original and optimized media may be at a higherresolution (often 1920×1080 pixels). The user might choose to use proxymedia because that is the only media available to the user, theprocessing speed of the user's computer is better suited to handlinglow-resolution media, the user plans on performing various otherresource-intensive tasks on the computer while also using theapplication, etc.

In addition to selecting which type of media should be used, someembodiments provide a playback quality selection option when usinghigh-resolution media. In some embodiments, the media-editingapplication can either decode the encoded media at full resolution(e.g., 1920×1080) or at a lower resolution (e.g., 960×540). In thiscase, the high quality option corresponds to a full resolution decodeand the better performance option corresponds to a lower resolutiondecode. Like using the low-resolution media, the low-resolution decodeoption is useful when working on a computer with lower processing speed,but no proxy media is available. Some embodiments provide a tool withinthe user interface (e.g., in the timeline or project library displayarea) that allows the user to toggle between low-resolution andhigh-resolution editing and playback. Such a user interface tool mightbe a toggle with two settings, or provide a choice of three settings. Insome embodiments, a user can use hotkeys to switch between resolutionsettings.

While FIG. 52 illustrates a playback settings tool that sets theresolution used for any project edited with the application, in someembodiments the application stores modifiable data for each projectindicating whether the project should be played back using high- orlow-resolution images. For example, a user could have a first projectfor which the application always uses high-resolution media and a secondproject for which the application always uses low-resolution media. Theuser could switch this property of the low-resolution project, forinstance, to use high-resolution media when additional computationalresources are available.

FIG. 53 conceptually illustrates the software architecture of a system5300 that enables such seamless transitioning between high- andlow-resolution editing. As with FIGS. 36, 37, and 43 above, the systemincludes a scheduling engine 3605, disk reader 3610, and decoder 3615,the operation of which has been described in detail above. As with FIG.43, FIG. 53 illustrates only the on-screen playback destination 4305,for which a resize and conversion to the display device RGB colorspaceis performed by the operation 4310.

The system 5300 also includes a playback media identifier 4315 andproject data 4325, also described above by reference to FIG. 43. Theplayback media identifier 4315 reads the current project state from theproject data 4325 and informs the scheduling engine as to which imagesit should schedule (i.e., which images are coming up in the playback)and the source file for that image (or multiple source files, if acomposite image).

The playback settings 5305 indicate a playback quality to the mediaidentifier 4315. In some embodiments, this indicates whether the mediaidentifier 4315 should instruct the scheduling engine 3605 to usehigh-resolution or low-resolution media for playback. In addition, asshown in FIG. 53, it may also include information regarding whether ahigh-resolution or low-resolution decode should be used. The latterinformation allows the scheduling engine to schedule the correct decodeoperation.

The playback media identifier 4315 receives (i) a setting indicatingwhether the application should retrieve high- or low-resolution mediaand (ii) project data (i.e., a set of data structures) that indicate themedia clips and times within those media clips that go into generatingan output image for a particular time. In some embodiments, this alsoindicates how the application will composite the images if multiplesource files are referenced. In some embodiments, each media clip refersto a particular asset, as shown in Section I.E above. As illustrated inFIG. 21, the asset may refer to multiple versions of a media file. Whenthe playback setting indicates low-resolution media, the mediaidentifier 4315 determines whether the asset includes a reference tosuch media, and if so selects this media for the scheduling engine 3605.When the playback setting indicates high-resolution media, someembodiments first determine whether the asset refers to ahigh-resolution transcoded version of the media. If this is unavailable,the playback media identifier 4315 selects the original media for thescheduling engine 3605, if the original media is available.

With the media file selected, the scheduling engine can schedule a diskread operation to read the image from the appropriate file in the mediastorage 5310. As shown in this figure, the media storage 5310 of someembodiments stores original media, high-resolution transcoded media(optimized), and low-resolution transcoded media (proxy). The image readfrom the disk can then be decoded by decoder 3615 using the specifieddecode and prepared for output to a display device.

B. Image Processing for High-Resolution and Low-Resolution Playback

The above subsection described the selection of a high-resolution orlow-resolution image for playback based on setting from the user. Thefollowing subsection describes how the media-editing application of someembodiments performs image-processing operations on the selected image.In some embodiments, these image-processing operations (e.g., blendingof two or more images, blurring images, scaling images, etc.) aredefined irrespective of the actual source file image size that theoperations will receive.

FIG. 54 conceptually illustrates data structures 5405 and 5410 for twodifferent images. The first image represented by data structure 5405 isa full-resolution image and the second image represented by datastructure 5410 is a quarter-resolution image. As shown, the images insome embodiments include a pixel buffer, a pixel transform, acolorspace, and a domain of definition. In some embodiments, theillustrated data structures are the structures used to send an image toa set of graphics processing operations defined by a render graph togenerate an output image for a particular time in a compositepresentation. The application of some embodiments retrieves imageinformation from a source file and decodes this information to get apixel buffer, then attaches the additional metadata (pixel transform,colorspace, and domain of definition). These images assume that fullresolution in this case is 1920×1080—in some embodiments, the fullresolution is defined by the asset, which gets its properties from theoriginal media. If the full resolution for the media is different fromthe project, then a conforming transformation will be added to therender graph to adjust the clip to the size of the project.

The pixel buffer of some embodiments is essentially a bitmap. In thefirst image 5405, the pixel buffer is a full-size 1920×1080 buffer,while the second image 5410 only has a quarter-size (half-width andhalf-height) 960×540 pixel buffer. The pixel buffer stores an orderedset of pixel values, which are values in a colorspace (i.e., thecolorspace stored in the image). For instance, in RGB space, each pixelis defined by a red value, a blue value, and a green value. Similarly,in Y′CbCr space, each pixel is defined by a luma value, ablue-difference value, and a red-difference value. The domain ofdefinition, in some embodiments, is the portion of an image that willend up being used in an output image. This may be the entire pixelbuffer, or a portion of the pixel buffer that cuts off the top andbottom or left and right portions.

The pixel transform, in some embodiments, is a transform that maps animage from image space to pixel space. In some embodiments, image spaceis a coordinate system in which an image is defined irrespective ofpixels. For instance, when the video properties of a project specify a1080p or 1080i format, the image space is 1920×1080. The media-editingapplication of some embodiments stores its data model in imagespace—thus, when a user defines video editing parameters (e.g., the sizeof a blur operation, the location of a small still image that iscomposited with a video, etc.), the application stores these parametersin image space. In some embodiments, the pixel transform is a 4×4matrix. Some embodiments, however, store the parameters as a percentageof the image size, which also enables easy conversion to different imagesizes, and enables easy copying of settings and effects from a firstproject with a first size to a second project with a second size.

The pixel transform for the optimized image 5405 is a unity transform.In some embodiments, this transform is a scale of 1 (because the imageis a full-resolution image, it does not need to be scaled between theoutput image space and its pixel space) multiplied by a translation of(960, 540). This translation accommodates the fact that the convenientcoordinates for image space place the origin in the center of the imagewhile pixel space is defined with the origin at the lower left. Inaddition to scaling and translation, the pixel transform can accommodateother movements in two (or three) dimensions, such as rotations,stretching, etc.

The pixel transform for the proxy image 5410 is a transform including ascale by one-half as well as the same origin translation as mentionedabove. Because the pixel transform is a transform from a 1920×1080 imagespace to a 960×540 pixel space, the transform is a scale by one-half inthe x and y directions. If the translation is performed before thescaling, then it is a translation of (960, 540). On the other hand, ifthe translation is performed after the scaling, then it is a translationof (480, 270). That is, the operations do not commute.

A simple example of the use of the pixel transform is for resampling aproxy image up to full-size in order to render a full-size version ofthe image. For example, during playback, some embodiments will renderimages ahead of time according to the render graph defined based on theedits in the timeline, and store the rendered images in memory (or todisk) for use during playback. These rendered images are stored at thesize requested by the project data structure (i.e., the size stored inthe project video properties) in some embodiments, so when the projecthas a resolution of 1920×1080, the images are rendered at this size.When displaying the image in the preview display area, the images aredownscaled to the size of the preview display.

FIG. 55 conceptually illustrates this process, assuming that there areno graphics processing operations necessary to prepare an output image.In this figure, a 960×540 pixel buffer is re-sampled by renderingresampling operation 5505 into a 1920×1080 pixel buffer. In someembodiments, this pixel buffer is stored in memory (e.g., RAM), or as arender file in non-volatile storage (e.g., the boot disk of the deviceon which the media-editing application is operating). This 1920×1080pixel buffer is then resampled for display into a pixel buffer havingthe size of the display area in which the image will be displayed. Forinstance, if the preview display area is 320×180 pixels, then thedisplay resampling operation 5510 will resample the 1920×1080 pixelbuffer into a 320×180 pixel buffer that can be displayed on the screen.In some embodiments, the graphics card of the device performs thisresampling as the graphics card outputs the pixels to the display.

FIG. 56 conceptually illustrates the first of these resamplingoperations. Specifically, this figure illustrates a 960×540 pixel buffer5605 that is resampled to create a 1920×1080 pixel buffer 5610. Togenerate this operation, the media-editing application of someembodiments applies an inverse of the proxy pixel transform stored inthe image to the pixel buffer in order to conceptually transform the setof pixels from pixel space to image space, then applies the pixeltransform associated with a full-size image to conceptually transformthe set of pixels from image space to pixel space. As shown, the inverseproxy transform involves a scale by two (and a translation) and therender transform involves no scale (and a reverse of the translation).

To perform this operation, some embodiments define a node in a rendergraph for the image that uses as input the matrix PT_(R)PT_(P) ⁻¹ (i.e.,the inverse proxy pixel transform followed by the render transform,applying matrix multiplication right to left as written, as isconvention). The operation then uses this matrix to scale up the pixelbuffer, and also performs pixel blending operations (i.e., so that thefour pixels in the bottom left corner of the output pixel buffer do notjust have the exact same values as the bottom left pixel in the inputpixel buffer).

FIG. 57 conceptually illustrates the second resampling operation, inwhich the 1920×1080 pixel buffer 5610 is resampled to create a 480×270pixel buffer 5705 for display in a preview display area of themedia-editing application. As with the operation shown in the previousfigure, the application applies an inverse render transform (which hasno scale) and a display transform (which in this case has a one-fourthscale). As shown, the resampling operation reduces the size of the pixelbuffer by a factor of four for display. In some embodiments, thisoperation (which involves blending of the pixel values) is performed bythe graphics card of the device as the graphics card is outputting thepixels to the display.

While in the illustrated case it may appear easier to just do a singleoperation (i.e., from the 960×540 pixel buffer to the 480×270 pixelbuffer) without the intermediate rendered image, in many cases there arenumerous additional graphics processing operations that go into creatingthe rendered image 5610. These operations may include color spaceconversions, blending images, rotating images, compositing two imagesbased on a color mask, etc.

Some embodiments, instead of rendering an image at full size (i.e., thesize defined by a project's video properties) and then downscaling thatimage for display, define image space during playback to be the size ofthe image actually displayed in the video. In this case, the images willbe rendered and stored in memory at the smaller size, and no downscalingwill be needed. However, if the user modifies the display size (e.g., byenlarging the preview display area) during playback, then theapplication will have to either re-render the output images or scale therendered images for output (as shown in FIG. 57).

As mentioned, some embodiments store the data model of the media-editingapplication in image space. The data model of some embodiments includesthe data structures described above in Section I.E. As mentioned in thatsection, many of the clip objects store effects stacks that specifyeffects to apply to the clip objects. These effects may includetransforms, pixel value modification operations, etc., and the values ofthe variables for the effects are stored in the output image space forthe clip object in some embodiments. Thus, when the video properties fora sequence specify a 1920×1080 image space, parameters for the imageprocessing operations assume that the operations apply to a 1920×1080pixel buffer. However, using the pixel transform for a particular image,these operations can be modified and performed on a pixel buffer of adifferent size.

FIGS. 58 and 59 conceptually illustrate two different processes forrendering an image at full-size 1920×1080 in which the applicationapplies an image-processing operation to the pixel buffer. In bothcases, the input pixel buffer (e.g., the output of a decode operation)is a 960×540 pixel buffer. The two rendering processes will be describedusing a blur operation as an example image-processing operation, but theprinciples described could apply to any such operation (e.g., adifferent effect, a transition, etc.).

FIG. 58 illustrates the case in which the media-editing applicationperforms the scaling operation 5805 first, followed by the imageprocessing operation 5810. As shown, initially the application appliesthe scaling operation to a 960×540 pixel buffer 5815 to scale the pixelbuffer up to a 1920×1080 output buffer 5820. This may be the sameoperation as shown in FIG. 56, that uses the inverse of the proxytransform stored in the data structure of the quarter-resolution imagefollowed by the unity transform for a full-size image. To the 1920×1080pixel buffer 5820, the application applies an image-processing operation5810 (specifically, an effect, transition, or other operation notrepresented by a pixel transform).

The media-editing application defines this operation with parameters(that may be user-entered) in image space. In the case of the bluroperation of some embodiments, the user defines a radius value (e.g.,100) for the operation. When performing the operation on a full-sizeimage, the application does not need to scale the parameters of theimage-processing operation. However, if the parameters specify alocation (e.g., for an iris in or iris out transition, a center for thecircle must be defined), then the application applies the translationaspect of the unity pixel transform to the coordinates for this locationto handle the move of the origin from the center of the image to thebottom left of the pixel buffer. As shown, the output of this operationis a modified 1920×1080 pixel buffer 5825.

FIG. 59 illustrates the case in which the application performs amodified image processing operation 5905 first, followed by the scalingoperation 5805. As shown, the same pixel buffer 5815 is input to theoperation 5905. In this case, the application scales the parameters ofthe image-processing operation in accordance with the pixel transformstored in the data structure with the pixel buffer 5815, which specifiesa scale factor of one-half as well as the usual origin translation.Thus, the application modifies the blur operation with a radius of 100into a blur operation with a radius of 50 (the original radius in imagespace multiplied by the pixel transform). The output of this bluroperation is a modified 960×540 pixel buffer 5910. The application thenapplies scaling operation 5805 to this modified pixel buffer 5910 togenerate the output 1920×1080 pixel buffer 5915. The scaling resamplingoperation 5805 is the same operation as applied in FIG. 58, but to adifferent pixel buffer. In some cases, the pixel buffer 5915 will be thesame as the pixel buffer 5825, depending on the image processingoperation that is applied, and whether it commutes with the scalingoperation. For example, applying the blur before scaling will generallyhave a slightly different result than applying the scaling first. Whilethe difference might not be noticeable to the human eye, the pixelvalues will be slightly different.

FIG. 60 conceptually illustrates a process 6000 of some embodiments forapplying an image processing operation to an image. The process 6000receives (at 6005) a pixel buffer and associated pixel transform for aninput image to an image processing operation. The image processingoperation may be an effect (e.g., a blur, filter, etc.), a transition,etc., that modifies the pixel values of the input image.

The process then identifies (at 6010) the parameters of the imageprocessing operation in image space. As stated, the image space of someembodiments is the size of the requested output image, and theapplication stores the parameters of the operation in this image space.The process 6000 converts (at 6015) the identified parameters to thepixel space of the image using the pixel transform of the image. As thepixel transform defines a conversion from image space into pixel space,the parameters will be translated, rotated, scaled, stretched, etc. tothe dimensions of the pixel buffer by the pixel transform. As mentioned,some embodiments actually store the parameters as percentages of theimage size, in which case the parameters may be converted to wholenumbers based on the actual size of the image.

The process then performs (at 6020) the image processing operation usingthe converted parameters. In some embodiments, the operations 6005-6015are performed for each image processing operation in an editing pipelinein order to define a render graph, and then the media-editingapplication performs these operations in sequential order to render theimage.

Within the editing pipeline, some embodiments use representationalimages rather than passing a pixel buffer to every node in the pipeline.When a node in the pipeline actually needs the pixels (e.g., to renderthe image), the application actually retrieves the image from the disk.The representational image of some embodiments stores a description ofhow to generate an image. For instance, the representational imagereferences a particular file on a particular disk from which the imagewill be retrieved, and includes a pixel transform for each node in theediting pipeline. In some cases, this allows inverse operations tocancel each other out, thereby saving on processing resources. Forinstance, if one node calls for a scale by four, and a second node callsfor a scale of one-half, then the media-editing application can simplyapply a scale of two when the image is actually retrieved. In someembodiments, the node modifies the pixel transform of an image ratherthan performing an actual transformation of the image. When possible,the pixels are actually transformed only once, rather than at each nodein the graph.

One result of the use of the pixel transform at each stage in the rendergraph is that the media-editing application can avoid downscaling imagesand then subsequently scaling the images back up, which would cause aloss in resolution (i.e., an image originally defined in HD will lookbetter than an image defined in SD and upconverted to HD). FIG. 61illustrates a timeline 6100 for a composite presentation as well as anoutput image 6105. The timeline 6100 is a sequence with video propertiesspecifying HD (1920×1080) output. Within the primary lane of thecollection structure stored in the sequence, the user has edited threeHD clips 6110-6120 and a SD clip 6125. Anchored off the SD clip is a HDtitle 6130 that is cropped to occupy only a portion of the bottom of theoutput image.

The playhead 6135 shows that the current image for the application todisplay is an image from the SD clip 6125 with the HD title 6130displayed over top. Because the timeline requests HD output, the outputimage is an upscaled version of the SD image from the SD clip, with thetitle pixels occupying a section at the bottom of the image. Because theSD image has a 4:3 aspect ratio and the HD output has a 16:9 aspectratio, the output image is pillar boxed. Some embodiments will fill the1920×1080 output image and cut off the top/bottom of the image, orstretch the image instead of using the pillar box.

As shown, the application never downscales the HD title to SD, butinstead outputs the title at its original HD resolution. Followingstrict compositing order, the HD title would be composited with the SDimage at the SD resolution, then the resultant image would be scaled upto HD for output. In some embodiments, the rendering engine recognizesthat the requested output is HD (based on the output pixel transform forthe primary sequence in the timeline), and therefore never downscalesthe title, as doing so would incur a needless loss of resolution.Instead, the application scales up the SD image to the HD size beforecompositing the images.

FIG. 62 conceptually illustrates a scene graph 6200 that the renderingengine converts to a render graph 6205 in order to render the image6105. The scene graph 6200 also indicates pixel transforms at eachoperation. For simplicity, the translations between the image spaceorigin and the pixel space origin in the pixel transforms are omitted.The output pixel transform in the scene graph 6200 has a scale of 1(i.e., it is outputting an image at the requested HD resolution). Thepixel transform for the blend operation (that blends the HD title in theforeground with the SD image in the background) also has a scale of 1,so as this matches with the pixel transform of the conform operation andthe pixel transform of the HD title image, no render graph node needs tobe defined to change the size of the image.

However, a blend render graph node is defined that takes as input theforeground HD image and the upscaled background SD image to output acomposite image. The HD title will often be defined as a full 1920×1080image that is mostly transparent (except for the actual title).

Continuing to traverse up the scene graph 6200, the foreground image(the title) has a pixel transform that matches the blend pixeltransform, so no processing is needed between these nodes—the HD bitmapis shown as an input to the blend node in the render graph 6205. Theconform effect also has a pixel transform with a scale of 1, because theoutput of the conform is a 1920×1080 image. The conform effect, in someembodiments, scales an image to fit a particular size (i.e., 1920×1080in this case).

The input of the conform effect has a pixel transform with a scale of4/9 (480/1080), while the output of the SD image has a pixel transformthat accounts for a pixel aspect ratio of 1.1:1, but has a scale of 1otherwise. As it is a bitmap, its image space is not 1920×1080. Whengenerating the render graph 6205, the media-editing application noticesthe difference in the pixel transforms and defines a node to scale theSD bitmap (the Image Transform Operation node). This is a node thatperforms an operation like that shown in FIG. 56 (i.e., an inverse ofthe 4/9 scale transform followed by the unity transform). Thus, therender graph 6205 is defined. The rendering engine can then use thisrender graph to generate an output image for the particular point in thetimeline 6100.

C. Missing Proxy Files

Section IV above describes certain cases when the media-editingapplication is unable to identify a file needed for output (e.g., to thepreview display area, as part of a filmstrip view of a media clip,etc.). When a user switches from high-resolution playback tolow-resolution playback (or vice versa), in some cases the media-editingapplication may not be able to access the needed file. For example, theuser might not have created a low-resolution (proxy) transcode of theoriginal media, but the application of some embodiments will not accessthe original media because the original media is at a higher resolutionthan is requested.

FIG. 63 conceptually illustrates a process 6300 of some embodiments fordisplaying an image (e.g., in a clip in the clip browser, in a clip inthe timeline, in the preview display, etc.). The process begins (at6305) by receiving a command to display an image. Specifically, theprocess receives a command to display an image from a particular time ina media clip, which references a particular time in an asset. As stated,this might be an image for display in the preview display area, within afilmstrip, etc. The command might also be a request for an image for anoperation such as the color waveform, color histogram, etc.

The process next identifies (at 6310) a playback quality setting. Theplayback setting may be set by a user of the media-editing applicationin some embodiments, as shown above in FIG. 52. In some embodiments, theuser may toggle the playback quality setting during the editing process(e.g., to reduce the use of computational resources). From the playbackquality setting, the process determines the particular size media fileto display (e.g., high-resolution, low-resolution).

The process then determines (at 6315) whether the media file with therequired image is available. For instance, if the application isrequesting a low-resolution image for a particular media clip, theprocess determines whether the asset referenced by that media cliprefers to a low-resolution transcoded file, and whether that transcodedfile currently exists. In some embodiments, when the applicationrequests a high-resolution image, the process determines whether theasset referenced by the media clip refers to a high-resolutiontranscoded file and whether the transcoded file currently exists. If thehigh-resolution transcode is unavailable, then the process attempts tofind the original media. When the asset does not refer to a file at therequested resolution and/or the file does not exist, the processdisplays (at 6320) an offline indicator for the image that indicatesthat the image is not available.

On the other hand, when the image can be found, the process performs (at6325) operations to display the image from the media file according tothe playback setting. Some embodiments perform disk read, decode, andimage processing operations as described in the above sections.

FIGS. 64 and 65 illustrate a workflow of some embodiments in which auser modifies the playback settings to use low-resolution media, thengenerates the low-resolution media so that the requested media isavailable to the application. FIG. 64 illustrates the effect ofmodifying the playback setting when no low-resolution media is availablefor at least one clip, in three stages 6410-6430. The first stage 6410illustrates a clip library and clip browser 6400. At this stage, theplayback setting calls for high-resolution media, and the media-editingapplication displays thumbnail images for all of the clips in the clipbrowser.

At stage 6420, the user has brought up the playback preferences HUD 6405of some embodiments, and switched the playback setting to use proxy(low-resolution) media. In some embodiments, the user selects apreferences menu option of the media-editing application and thenselects the playback tab. The user then selects the “Use Proxy Media”radio button. Shown at stage 6430, this causes the clip library todisplay a missing clip/file image in the thumbnail for clip 6415. Someembodiments use a same image regardless of why the file is missing,while other embodiments display different images for missing proxyfiles, missing high-resolution files, missing events, missing clips,etc. (although when displayed in the clip browser, the event and clipwould generally not be missing).

FIG. 65 illustrates the generation of low-resolution media for the clip,which resolves the broken file reference, over three stages 6510-6530.The first stage 6510 illustrates the clip library and browser 6400. Theuser has selected the clip 6415 and opened a pop-up menu for the clipthat includes a selectable option of “Optimize Media”, which is anoption to create transcoded versions of the media. In some embodiments,the user brings up the pop-up menu with a particular type of selectioninput (e.g., right-clicking, two-finger-tapping on a touchscreen, etc.).

Selection of this option brings up the dialog box 6500 shown in stage6520. The dialog box includes an option to create optimized media thatis grayed out, and a selected option to create proxy media. Thehigh-resolution transcode option may be grayed out because ahigh-resolution transcode already exists, or because the original mediais already in a format suitable for editing (e.g., without any temporalcompression).

Selecting the low-resolution transcode instructs the application togenerate a low-resolution transcode file, as described above. As shownat stage 6530, after the generation of such a file, the clip 6415displays a thumbnail image from its newly generated low-resolutiontranscode file rather than the missing proxy image.

VI. Background Tasks

The above sections describe the performance of a number of tasks by themedia-editing application of some embodiments. These tasks includeimporting media, transcoding media, analyzing media, rendering media(e.g., for playback), etc. The media-editing application performs someof these operations in the background in some embodiments, pausing thetasks to free up processing resources for other operations needed inreal-time, such as media playback.

FIG. 66 conceptually illustrates a state diagram 6600 of someembodiments relating to the operation of background tasks for amedia-editing application. One of ordinary skill will recognize that themedia-editing application may perform a multitude of other actions andthat the states shown in this diagram are only those relating to theperformance of background tasks. In some embodiments, the applicationstores a background task queue that keeps track of the tasks to perform.The task queue may be managed either by the media-editing application orby an operating system of the device on which the application operates.

As shown, during normal operation of the task queue in the background,the application is at state 6605. At this stage, the background taskqueue performs operation in a normal fashion. FIG. 69, described below,illustrates normal operation performance according to some embodiments.In some embodiments, the application supports task serialization withinthe queue, which allows for the use of rules that prevent contentionfrom multiple tasks over shared resources (e.g., processor time) orlocks. There may be multiple operations in the task queue, includingimport operations (e.g., copying files from an external device or folderto the application media storage), encoding operations (e.g., bothhigh-resolution and low-resolution encodes), analysis operations (e.g.,face detection, audio enhancement, shake detection, color balancing,etc.), background rendering (i.e., generating timeline output for lateruse according to the current setup of the composite presentation), mediamanagement (e.g., deletion of media that is not used for a project,copying of used media, etc.), and sharing (e.g., exporting to anotherformat for distribution).

Some embodiments provide a user interface window that enables the userto view the progress of such tasks, pause and restart such tasks, etc.FIG. 67 illustrates an example of such a GUI window 6700. As can beseen, the window 6700 includes status information for optimization andanalysis, media import, media management, rendering, and sharing. Theoptimization and analysis and media import are currently in progress(e.g., because the user is transcoding media upon import), and thereforethe window 6700 shows status bars along with pause and stop buttons forthese tasks. In addition, because the tasks are in progress, a user canselect the item to see the progress for individual clip. FIG. 68illustrates a background task GUI window 6800 while the applicationperforms both encoding and/or analysis as well as background rendering.In this case, the user has opened the optimization and analysis tab toreview the status of the different clips. As shown, the application hasonly started performing the encoding and analysis operations on one ofthe media clips, which is 20% complete.

During the course of this normal operation, users may pause and resumetasks in some embodiments (e.g., through the user interface). As shownin FIG. 66, when a user pauses a task, the application transitions tostate 6610 to pause the task, then returns to normal operation (at state6605) for any other ongoing tasks. When the user unpauses a paused task,the application transitions to state 6615 to resume the task, thenreturns to normal operation (at state 6605) for the resumed task as wellas any other ongoing tasks.

Users may also cancel tasks, which clears the canceled task from thequeue. As shown, when a user cancels a task, the application transitionsto state 6620 to cancel the task and remove the task from the backgroundtask queue, then returns to normal operation (at state 6605) for anyother ongoing tasks. In some embodiments, the user can pause or cancelthe background tasks through a user interface such as that shown in FIG.68.

In some embodiments, the media-editing application performs backgroundtasks when processing and memory resources are available, but stopsthese tasks when resources are needed for other operations. As shown,when user actions result in a transition to low-overhead mode, theapplication transitions to state 6625. The application may transition tothis mode when instructed to play back a clip or set of clips, when auser skims through a clip, when a user performs editing operations suchas trimming a clip or adding effects, etc. In low-overhead mode, theapplication prevents new tasks from entering the background task queue,and attempts to cancel or pause the remaining tasks. In someembodiments, each task has a value set that indicates whether the taskshould be paused, canceled, or allowed to continue running when theapplication enters low-overhead mode. For instance, the applicationpauses image analysis tasks in some embodiments, while continuing to runthe analysis of which parts of a timeline need to be rendered.

The application then transitions to state 6630, at which point the onlybackground tasks performed by the application are those flagged to runduring low-overhead mode. In addition, the application may be performingwhatever additional tasks required the entrance of low-overhead mode inthe first place (e.g., playing back a sequence). When actions result inexiting low-overhead mode, the application transitions to 6635. At thisstate, the application resumes any paused tasks and allows new tasks tojoin the queue. In some embodiments, the application may exitlow-overhead mode when playback is finished, the user has released aselection of the playhead, or has not interacted with a clip forskimming for a predetermined period of time (e.g., two seconds). Theapplication then transitions to 6605 to resume normal operation of thetask queue in the background.

In some embodiments, the tasks will also pause, implement, or cancelthemselves at an appropriate time (e.g., when not holding resources, soas to avoid deadlock situations). For instance, as shown in FIG. 68,some embodiments perform all transcoding and analysis operations on afirst clip before beginning to perform these operations on a secondclip. In some embodiments, some of the background tasks may implementthe pause/resume and cancel in a task-specific manner by mapping a pauseor cancel request into an appropriate call to the scheduling engine(e.g., a pause request that causes the scheduling engine to stopgenerating new frames and sending them to the task), while other tasksimplement pause/resume/cancel by using a shared infrastructure thatprovides simplified support for pausing and cancelling (e.g., methods ofa superclass that can be used by the various different tasks in order tohandle the pausing). Some embodiments use the playback engine to pauseoperations that require the playback engine for image data and have adefined start and end, while using the shared infrastructure foriterative tasks that continue unless paused.

As mentioned, FIG. 69 conceptually illustrates a process 6900 of someembodiments for normal operation of a task within the background taskqueue. The process 6900 starts when a task begins. This process assumesthat the task application at least starts performing the task, asopposed to the task entering the queue and being paused before evenstarting. As shown, the process obtains (at 6905) a lock for the task.In some embodiments, this lock is a mutex that prevents data used by thetask from being changed by a different task (e.g., being performed by adifferent processor thread). This data may be a frame of image data, athumbnail, a data structure that is part of a project, etc. For example,in order for a render task to generate a particular thumbnail, theprocess would obtain a lock for the task that prevents the modificationof the project data (i.e., the clips) that define which images to usefor the thumbnail as well as the image data that goes into thethumbnail.

Next, the process performs (at 6910) a unit of work of the task. As thetasks may run the gamut of media-editing application operations, a unitof work may also be varied. For example, it may involve performing anoperation on an image (e.g., encoding an image, analyzing an image,resizing an image, etc.), performing an operation on a part of an image,modifying a file or a portion of a file, etc. With the unit of workperformed, the process releases (at 6915) the lock, making the data usedby the task available for modification by other tasks.

The process 6900 then updates (at 6920) the task progress. In someembodiments, the task queue keeps track of all of the work that needs tobe performed by each task, and the process updates this queue toindicate that the particular task performed is now one unit closer tocompletion. The process then determines (at 6925) whether to continueperforming the task. In some embodiments, this determination is based onwhether the task has been completed, as well as whether the task hasbeen paused or canceled (e.g., because of a higher priority task beingperformed). When the process 6900 will continue performing the task, theprocess returns to 6905 to obtain another lock for the task. Otherwise,the process ends.

VII. Software Architecture

In some embodiments, the processes described above are implemented assoftware running on a particular machine, such as a computer or ahandheld device, or stored in a machine-readable medium. FIG. 70conceptually illustrates the software architecture of a media editingapplication 7000 of some embodiments. In some embodiments, the mediaediting application is a stand-alone application or is integrated intoanother application, while in other embodiments the application might beimplemented within an operating system. Furthermore, in someembodiments, the application is provided as part of a server-basedsolution. In some such embodiments, the application is provided via athin client. That is, the application runs on a server while a userinteracts with the application via a separate machine remote from theserver. In other such embodiments, the application is provided via athick client. That is, the application is distributed from the server tothe client machine and runs on the client machine.

The media editing application 7000 includes a user interface (UI)interaction and generation module 7005, a media ingest module 7010,editing modules 7015, rendering engine 7020, playback module 7025,real-time analysis modules 7030, encoding modules 7035, backgroundanalysis modules 7040, and task manager 7045.

The figure also illustrates stored data associated with themedia-editing application: source files 7050, events data 7055, projectdata 7060, and render files 7065. In some embodiments, the source files7050 store media files (e.g., video files, audio files, combined videoand audio files, etc.) imported into the application. The source files7050 of some embodiments also store transcoded versions of the importedfiles as well as analysis data (e.g., people detection data, shakedetection data, color balance data, etc.). The events data 7055 storesthe events information used by some embodiments to populate the cliplibrary and clip browser. The events data may be a set of clip objectdata structures stored as one or more SQLite database files (or otherformat) in some embodiments. The project data 7060 stores the projectinformation used by some embodiments to specify a composite presentationin the timeline. The project data may also be a set of clip object datastructures stored as one or more SQLite database files (or other format)in some embodiments. The render files 7065 of some embodiments mayinclude thumbnail-sized images for display in the clip browser ortimeline, audio waveform displays for media clips, as well as renderedsegments of a timeline sequence for use in playback. In someembodiments, the four sets of data 7050-7065 are stored in one physicalstorage (e.g., an internal hard drive, external hard drive, etc.). Insome embodiments, the data may be split between multiple physicalstorages. For instance, the source files might be stored on an externalhard drive with the events data, project data, and render files on aninternal drive. Some embodiments store events data with their associatedsource files and render files in one set of folders, and the projectdata with associated render files in a separate set of folders.

FIG. 70 also illustrates an operating system 7070 that includes inputdevice driver(s) 7075, display module 7080, and media import module7085. In some embodiments, as illustrated, the device drivers 7075,display module 7080, and media import module 7085 are part of theoperating system even when the media editing application 7000 is anapplication separate from the operating system.

The input device drivers 7075 may include drivers for translatingsignals from a keyboard, mouse, touchpad, tablet, touchscreen, etc. Auser interacts with one or more of these input devices, which sendsignals to their corresponding device driver. The device driver thentranslates the signals into user input data that is provided to the UIinteraction and generation module 7005.

The present application describes a graphical user interface thatprovides users with numerous ways to perform different sets ofoperations and functionalities. In some embodiments, these operationsand functionalities are performed based on different commands that arereceived from users through different input devices (e.g., keyboard,trackpad, touchpad, mouse, etc.). For example, the present applicationillustrates the use of a cursor in the graphical user interface tocontrol (e.g., select, move) objects in the graphical user interface.However, in some embodiments, objects in the graphical user interfacecan also be controlled or manipulated through other controls, such astouch control. In some embodiments, touch control is implemented throughan input device that can detect the presence and location of touch on adisplay of the device. An example of such a device is a touch screendevice. In some embodiments, with touch control, a user can directlymanipulate objects by interacting with the graphical user interface thatis displayed on the display of the touch screen device. For instance, auser can select a particular object in the graphical user interface bysimply touching that particular object on the display of the touchscreen device. As such, when touch control is utilized, a cursor may noteven be provided for enabling selection of an object of a graphical userinterface in some embodiments. However, when a cursor is provided in agraphical user interface, touch control can be used to control thecursor in some embodiments.

The display module 7080 translates the output of a user interface for adisplay device. That is, the display module 7080 receives signals (e.g.,from the UI interaction and generation module 7005) describing whatshould be displayed and translates these signals into pixel informationthat is sent to the display device. The display device may be an LCD,plasma screen, CRT monitor, touchscreen, etc.

The media import module 7085 receives media files (e.g., audio files,video files, etc.) from storage devices (e.g., external drives,recording devices, etc.) through one or more ports (e.g., a USB port,Firewire port, etc.) of the device on which the application 7000operates and translates this media data for the media-editingapplication or stores the data directly onto a storage of the device.

The UI interaction and generation module 7005 of the media editingapplication 7000 interprets the user input data received from the inputdevice drivers and passes it to various modules, including the mediaingest module 7010, the editing modules 7015, the rendering engine 7020,the playback module 7025, the real-time analysis modules 7030, and thetask manager 7045. The UI interaction module also manages the display ofthe UI, and outputs this display information to the display module 7080.This UI display information may be based on information from the editingmodules 7025, the playback module 7025, the real-time analysis modules7030, the task manager, and the data 7050-7065. In addition, the module7005 may generate portions of the UI based solely on user input—e.g.,when a user moves an item in the UI that only affects the display, notany of the other modules, such as moving a window (e.g., the backgroundtasks window) from one side of the UI to the other. In some embodiments,the UI interaction and generation module 7005 generates a basic GUI andpopulates the GUI with information from the other modules and storeddata.

The media ingest module 7010 manages the import of source media into themedia-editing application 7000. Some embodiments, as shown, receivesource media from the media import module 7085 of the operating system7070. The media ingest module 7010 receives instructions through the UImodule 7005 as to which files should be imported, then instructs themedia import module 7085 to enable this import (e.g., from an externaldrive, from a camera, etc.). The media ingest module 7010 stores thesesource files 7050 in specific file folders associated with theapplication. In some embodiments, the media ingest module 7010 alsomanages the creation of event data structures upon import of sourcefiles and the creation of the clip and asset data structures containedin the events.

The editing modules 7015 include a variety of modules for editing mediain the clip browser as well as in the timeline. The editing modules 7015handle the creation of projects, addition and subtraction of clips fromprojects, trimming or other editing processes within the timeline,application of effects and transitions, or other editing processes. Insome embodiments, the editing modules 7015 create and modify project andclip data structures in both the event data 7055 and the project data7060.

The rendering engine 7020 handles the rendering of images for themedia-editing application. As shown, the rendering engine 7020 of someembodiments includes a render graph generator 7021, a scheduler 7022,and image processing operations 7023. The rendering engine manages thecreation of images for the media-editing application. When an image isrequested by a destination within the application (e.g., the playbackmodule 7025, a real-time analysis module 7030, an encoding modules 7035,or a background analysis module 7040), the rendering engine outputs therequested image according to the project or event data. The renderingengine retrieves the project data or event data that identifies how tocreate the requested image and the render graph generator 7021 generatesa render graph that is a series of nodes indicating either images toretrieve from the source files 7050 or operations to perform on thesource files. The scheduler 7022 schedules the retrieval of thenecessary images through disk read operations and the decoding of thoseimages. The image processing operations 7023 are the various operationsperformed on the images to generate an output image. In someembodiments, these operations include blend operations, effects (e.g.,blur or other pixel value modification operations), color spaceconversions, resolution transforms, etc. The image processing operations7023 in some embodiments are actually part of the operating system andare performed by a GPU or CPU of the device on which the application7000 operates. The output of the rendering engine (a rendered image) maybe stored in the render files 7065 or sent to a destination foradditional processing or output.

The playback module 7025 handles the playback of images (e.g., in apreview display area of the user interface). Some embodiments do notinclude a playback module and the rendering engine directly outputs itsimages to the UI module 7010 for integration into the GUI, or directlyto the display module 7080 for display at a particular portion of thedisplay device.

The real-time analysis modules 7030 include modules for generating acolor waveform, color histogram, vectorscope, etc. These modules analyzeimages being output in real-time and generate their own output. Thereal-time analysis modules 7030 send this output to the UI interactionand generation module 7005 for integration into the UI output. In someembodiments, these modules use the same images being output by therendering engine for playback, though may require the images in adifferent resolution or colorspace than the playback module 7025.

The encoding modules 7035 and background analysis modules 7040 performbackground processes on images output by the rendering engine. Theencoding modules 7035 perform at least two different types of encodingon source media (e.g., a high-resolution encode and a low-resolutionencode). Some embodiments store the encoded media in the source files7050 along with the original media. The background analysis modules 7040perform various non-real-time analysis processes on the images and storedata files indicating the results in the source files 7050 in someembodiments. These processes may include person detection (e.g., throughface detection), color balancing, and shake detection.

The task manager 7045 of some embodiments manages background tasks andtheir queue. As described above, the background tasks may includebackground rendering, encoding, analysis, etc. The task manager 7045receives tasks to perform (e.g., from the UI module 7005) or othermodules and manages the performance of these tasks. The task manager mayinform the rendering engine 7020 when it should be rendering images forthese background tasks, when it should pause the tasks, etc. Though notshown, in some embodiments, the task manager also communicates with thebackground analysis modules 7040 and the encoding modules 7035.

While many of the features of media-editing application 7000 have beendescribed as being performed by one module (e.g., the UI interaction andgeneration module 7005, the media ingest manager 7010, etc.), one ofordinary skill in the art will recognize that the functions describedherein might be split up into multiple modules. Similarly, functionsdescribed as being performed by multiple different modules might beperformed by a single module in some embodiments (e.g., the playbackmodule 7025 might be part of the UI interaction and generation module7005).

VIII. Electronic System

Many of the above-described features and applications are implemented assoftware processes that are specified as a set of instructions recordedon a computer readable storage medium (also referred to as computerreadable medium). When these instructions are executed by one or morecomputational or processing unit(s) (e.g., one or more processors, coresof processors, or other processing units), they cause the processingunit(s) to perform the actions indicated in the instructions. Examplesof computer readable media include, but are not limited to, CD-ROMs,flash drives, random access memory (RAM) chips, hard drives, erasableprogrammable read only memories (EPROMs), electrically erasableprogrammable read-only memories (EEPROMs), etc. The computer readablemedia does not include carrier waves and electronic signals passingwirelessly or over wired connections.

In this specification, the term “software” is meant to include firmwareresiding in read-only memory or applications stored in magnetic storagewhich can be read into memory for processing by a processor. Also, insome embodiments, multiple software inventions can be implemented assub-parts of a larger program while remaining distinct softwareinventions. In some embodiments, multiple software inventions can alsobe implemented as separate programs. Finally, any combination ofseparate programs that together implement a software invention describedhere is within the scope of the invention. In some embodiments, thesoftware programs, when installed to operate on one or more electronicsystems, define one or more specific machine implementations thatexecute and perform the operations of the software programs.

FIG. 71 conceptually illustrates an electronic system 7100 with whichsome embodiments of the invention are implemented. The electronic system7100 may be a computer (e.g., a desktop computer, personal computer,tablet computer, etc.), phone, PDA, or any other sort of electronic orcomputing device. Such an electronic system includes various types ofcomputer readable media and interfaces for various other types ofcomputer readable media. Electronic system 7100 includes a bus 7105,processing unit(s) 7110, a graphics processing unit (GPU) 7115, a systemmemory 7120, a network 7125, a read-only memory 7130, a permanentstorage device 7135, input devices 7140, and output devices 7145.

The bus 7105 collectively represents all system, peripheral, and chipsetbuses that communicatively connect the numerous internal devices of theelectronic system 7100. For instance, the bus 7105 communicativelyconnects the processing unit(s) 7110 with the read-only memory 7130, theGPU 7115, the system memory 7120, and the permanent storage device 7135.

From these various memory units, the processing unit(s) 7110 retrievesinstructions to execute and data to process in order to execute theprocesses of the invention. The processing unit(s) may be a singleprocessor or a multi-core processor in different embodiments. Someinstructions are passed to and executed by the GPU 7115. The GPU 7115can offload various computations or complement the image processingprovided by the processing unit(s) 7110. In some embodiments, suchfunctionality can be provided using CoreImage's kernel shading language.

The read-only-memory (ROM) 7130 stores static data and instructions thatare needed by the processing unit(s) 7110 and other modules of theelectronic system. The permanent storage device 7135, on the other hand,is a read-and-write memory device. This device is a non-volatile memoryunit that stores instructions and data even when the electronic system7100 is off. Some embodiments of the invention use a mass-storage device(such as a magnetic or optical disk and its corresponding disk drive) asthe permanent storage device 7135.

Other embodiments use a removable storage device (such as a floppy disk,flash memory device, etc., and its corresponding drive) as the permanentstorage device. Like the permanent storage device 7135, the systemmemory 7120 is a read-and-write memory device. However, unlike storagedevice 7135, the system memory 7120 is a volatile read-and-write memory,such a random access memory. The system memory 7120 stores some of theinstructions and data that the processor needs at runtime. In someembodiments, the invention's processes are stored in the system memory7120, the permanent storage device 7135, and/or the read-only memory7130. For example, the various memory units include instructions forprocessing multimedia clips in accordance with some embodiments. Fromthese various memory units, the processing unit(s) 7110 retrievesinstructions to execute and data to process in order to execute theprocesses of some embodiments.

The bus 7105 also connects to the input and output devices 7140 and7145. The input devices 7140 enable the user to communicate informationand select commands to the electronic system. The input devices 7140include alphanumeric keyboards and pointing devices (also called “cursorcontrol devices”), cameras (e.g., webcams), microphones or similardevices for receiving voice commands, etc. The output devices 7145display images generated by the electronic system or otherwise outputdata. The output devices 7145 include printers and display devices, suchas cathode ray tubes (CRT) or liquid crystal displays (LCD), as well asspeakers or similar audio output devices. Some embodiments includedevices such as a touchscreen that function as both input and outputdevices.

Finally, as shown in FIG. 71, bus 7105 also couples electronic system7100 to a network 7125 through a network adapter (not shown). In thismanner, the computer can be a part of a network of computers (such as alocal area network (“LAN”), a wide area network (“WAN”), or an Intranet,or a network of networks, such as the Internet. Any or all components ofelectronic system 7100 may be used in conjunction with the invention.

Some embodiments include electronic components, such as microprocessors,storage and memory that store computer program instructions in amachine-readable or computer-readable medium (alternatively referred toas computer-readable storage media, machine-readable media, ormachine-readable storage media). Some examples of such computer-readablemedia include RAM, ROM, read-only compact discs (CD-ROM), recordablecompact discs (CD-R), rewritable compact discs (CD-RW), read-onlydigital versatile discs (e.g., DVD-ROM, dual-layer DVD-ROM), a varietyof recordable/rewritable DVDs (e.g., DVD-RAM, DVD-RW, DVD+RW, etc.),flash memory (e.g., SD cards, mini-SD cards, micro-SD cards, etc.),magnetic and/or solid state hard drives, read-only and recordableBlu-Ray® discs, ultra density optical discs, any other optical ormagnetic media, and floppy disks. The computer-readable media may storea computer program that is executable by at least one processing unitand includes sets of instructions for performing various operations.Examples of computer programs or computer code include machine code,such as is produced by a compiler, and files including higher-level codethat are executed by a computer, an electronic component, or amicroprocessor using an interpreter.

While the above discussion primarily refers to microprocessor ormulti-core processors that execute software, some embodiments areperformed by one or more integrated circuits, such as applicationspecific integrated circuits (ASICs) or field programmable gate arrays(FPGAs). In some embodiments, such integrated circuits executeinstructions that are stored on the circuit itself. In addition, someembodiments execute software stored in programmable logic devices(PLDs), ROM, or RAM devices.

As used in this specification and any claims of this application, theterms “computer”, “server”, “processor”, and “memory” all refer toelectronic or other technological devices. These terms exclude people orgroups of people. For the purposes of the specification, the termsdisplay or displaying means displaying on an electronic device. As usedin this specification and any claims of this application, the terms“computer readable medium,” “computer readable media,” and “machinereadable medium” are entirely restricted to tangible, physical objectsthat store information in a form that is readable by a computer. Theseterms exclude any wireless signals, wired download signals, and anyother ephemeral signals.

While the invention has been described with reference to numerousspecific details, one of ordinary skill in the art will recognize thatthe invention can be embodied in other specific forms without departingfrom the spirit of the invention. In addition, a number of the figures(including FIGS. 5, 8, 20, 22, 29, 30, 35, 38, 45, 60, 63, and 69)conceptually illustrate processes. The specific operations of theseprocesses may not be performed in the exact order shown and described.The specific operations may not be performed in one continuous series ofoperations, and different specific operations may be performed indifferent embodiments. Furthermore, the process could be implementedusing several sub-processes, or as part of a larger macro process. Thus,one of ordinary skill in the art would understand that the invention isnot to be limited by the foregoing illustrative details, but rather isto be defined by the appended claims.

We claim:
 1. A method for editing a composite presentation in amedia-editing application, the composite presentation comprising aplurality of media clips, the method comprising: receiving an importcommand to import a media file into the media-editing application froman external device; upon receipt of the import command, automaticallycreating a media clip to represent the media file in the media editingapplication, the media clip comprising a data structure that refers tothe media file on the external device; during the import of the mediafile from the external device, receiving user input to add the mediaclip to the composite presentation being edited by the user; in responseto the input, adding the media clip, which comprises the data structurereferring to the media file on the external device, to the plurality ofmedia clips in the composite presentation such that the compositepresentation refers to the media file on the external device; and uponcompletion of the import of the media file from the external device,automatically modifying the reference in the media clip's data structureto refer to a copy of the media file on a local device rather than onthe external device such that the composite presentation refers to themedia file on the local device.
 2. The method of claim 1, wherein theexternal device is a camera.
 3. The method of claim 1, wherein theexternal device is an external hard disk.
 4. The method of claim 1,wherein the media clip comprises an asset data structure that (i)initially comprises a reference to the media file on the external deviceand (ii) has the reference to the media file on the external devicereplaced with a reference to the copy of the media file on the localdevice after the media file is imported.
 5. The method of claim 4,wherein the media clip further comprises a clip data structure thatrefers to the asset data structure and is independent of a location ofthe media file.
 6. The method of claim 5 further comprising, uponreceiving the user input to add the media clip to the compositepresentation, duplicating the clip data structure within a datastructure for the composite presentation, the duplicate clip datastructure also referencing the asset data structure independent of thelocation of the media file.
 7. The method of claim 1 further comprisinggenerating thumbnail images for display in a graphical user interface ofthe media-editing application from the media file stored on the externaldevice during the import of the media file.
 8. The method of claim 1further comprising copying the media file from the external device tothe local device.
 9. The method of claim 8, wherein the copied mediafile is stored in a particular folder associated with the media-editingapplication on the local device.
 10. The method of claim 1, wherein thelocal device is a boot disk of a computer on which the media-editingapplication operates.
 11. A non-transitory machine readable mediumstoring a program which when executed by at least one processor edits acomposite presentation comprising a plurality of media clips in amedia-editing application, the program comprising sets of instructionsfor: receiving an import command to import a media file into themedia-editing application from an external device; automaticallycreating, upon receipt of the import command, a media clip to representthe media file in the media editing application, the media clipcomprising a data structure that refers to the media file on theexternal device; receiving, during the import of the media file from theexternal device, user input to add the media clip to the compositepresentation being edited by the user; adding, in response to the input,the media clip, which comprises the data structure referring to themedia file on the external device, to the plurality of media clips inthe composite presentation such that the composite presentation refersto the media file on the external device; and automatically modifying,upon completion of the import of the media file from the externaldevice, the reference in the media clip's data structure to refer to acopy of the media file on a local device rather than on the externaldevice such that the composite presentation refers to the media file onthe local device.
 12. The non-transitory machine readable medium ofclaim 11, wherein the external device is a camera.
 13. Thenon-transitory machine readable medium of claim 11, wherein the externaldevice is an external hard disk.
 14. The non-transitory machine readablemedium of claim 11, wherein the media clip comprises an asset datastructure that (i) initially comprises a reference to the media file onthe external device and (ii) has the reference to the media file on theexternal device replaced with a reference to the copy of the media fileon the local device after the media file is imported.
 15. Thenon-transitory machine readable medium of claim 14, wherein the mediaclip further comprises a clip data structure that refers to the assetdata structure and is independent of a location of the media file. 16.The non-transitory machine readable medium of claim 15, wherein theprogram further comprises a set of instructions for duplicating, uponreceiving the user input to add the media clip to the compositepresentation, the clip data structure within a data structure for thecomposite presentation, the duplicate clip data structure alsoreferencing the asset data structure independent of the location of themedia file.
 17. The non-transitory machine readable medium of claim 11,wherein the program further comprises a set of instructions forgenerating thumbnail images for display in a graphical user interface ofthe media-editing application from the media file stored on the externaldevice during the import of the media file.
 18. The non-transitorymachine readable medium of claim 11, wherein the program furthercomprises a set of instructions for copying the media file from theexternal device to the local device.
 19. The non-transitory machinereadable medium of claim 18, wherein the copied media file is stored ina particular folder associated with the media-editing application on thelocal device.
 20. The non-transitory machine readable medium of claim11, wherein the local device is a boot disk of a computer on which themedia-editing application operates.
 21. An apparatus comprising: a setof processing units for executing sets of instructions; and amachine-readable medium storing a program which when executed by atleast one of the processing units edits a composite presentationcomprising a plurality of media clips in a media-editing application,the program comprising sets of instructions for: receiving an importcommand to import a media file into the media-editing application froman external device; automatically creating, upon receipt of the importcommand, a media clip to represent the media file in the media editingapplication, the media clip comprising a data structure that refers tothe media file on the external device; receiving, during the import ofthe media file from the external device, user input to add the mediaclip to the composite presentation being edited by the user; adding, inresponse to the input, the set of media clip, which comprises the datastructure referring to the media file on the external device, to theplurality of media clips in the composite presentation such that thecomposite presentation refers to the media file on the external device;and automatically modifying, upon completion of the import of the mediafile from the external device, the reference in the media clip's datastructure to refer to a copy of the media file on a local device ratherthan on the external device such that the composite presentation refersto the media file on the local device.
 22. The apparatus of claim 21,wherein the external device is a camera.
 23. The apparatus of claim 21,wherein the external device is an external hard disk.
 24. The apparatusof claim 21, wherein the media clip comprises an asset data structurethat (i) initially comprises a reference to the media file on theexternal device and (ii) has the reference to the media file on theexternal device replaced with a reference to the copy of the media fileon the local device after the media file is imported.
 25. The apparatusof claim 24, wherein the media clip further comprises a clip datastructure that refers to the asset data structure and is independent ofa location of the media file.